Information processing device, information processing method, and program

ABSTRACT

To efficiently use radio resources. 
     An information processing device is an information processing device that receives a packet. The information processing device is an information processing device that includes a control unit. The control unit included in the information processing device performs control such that reception of a packet is stopped during the reception according to a first condition. The control unit included in the information processing device performs control such that reception of the packet is stopped during the reception and an operation is performed assuming that a carrier sense is an idle state for a time from start of the reception of the packet to stop of the reception of the packet according to a second condition.

TECHNICAL FIELD

The present technology relates to an information processing device.Specifically, the present technology relates to an informationprocessing device and an information processing method of exchanginginformation using wireless communication and a program capable ofcausing a computer to perform the method.

BACKGROUND ART

In the related art, there are wireless communication technologies forexchanging information using wireless communication. For example,communication methods (for example, autonomous distributed wirelessnetworks) of autonomously performing mutual connection betweeninformation processing devices that approach each other have beenproposed. By using such communication methods, it is possible toexchange information between two information processing devices usingwireless communication even when connection is not made with wiredcircuits.

In autonomous distributed wireless networks, carrier senses are adoptedas adjustment methods of avoiding packet collision at the time ofcommunication between information processing devices.

For example, wireless communication devices performing transmissionsuppression by dynamically setting carrier sense level thresholds usingdesired wave powers as standards have been proposed (for example, seePatent Literature 1).

CITATION LIST Patent Literature

Patent Literature 1: JP 2007-142722A

SUMMARY OF INVENTION Technical Problem

In the technologies of the above-described related art, even whentransmission is possible at reception signal intensities equal to orless than the carrier sense level thresholds, transmission can be setnot to be performed at the time of a desired-wave-to-interference powerratio at which transmission is erroneous.

However, when the number of information processing devices configured ina network increases, excessive transmission suppression occurs and thereis a concern of transmission efficiency of an entire systemdeteriorating. Accordingly, it is important to efficiently use radioresources while maintaining communication quality.

It is desirable to provide the present technology capable of efficientlyusing radio resources.

Solution to Problem

The present technology has been made to solve the above problem. A firstaspect of the present technology is an information processing deviceincluding a control unit configured to perform control such thatreception of a packet is stopped during the reception according to afirst condition and an operation is performed assuming that a carriersense is an idle state for a time from start of the reception of thepacket to stop of the reception of the packet according to a secondcondition, an information processing method thereof, and a programcausing a computer to perform the method. Thus, it is possible to obtainan operational effect in which the reception of the packet is stoppedduring the reception according to the first condition and the operationis performed assuming that the carrier sense is in the idle state forthe time from start of the reception of the packet to the stop of thereception of the packet according to the second condition.

In the first aspect, when the second condition is satisfied after thestop of the reception of the packet, the control unit may performcontrol such that a latency time corresponding to an inter frame space(IFS) does not occur. Thus, it is possible to obtain an operationaleffect in which, when the second condition is satisfied after the stopof the reception of the packet, the control is performed such that thelatency time corresponding to the IFS does not occur.

In the first aspect, when the second condition is satisfied after thestop of the reception of the packet, the control unit may performcontrol such that a time length from a transition time of the carriersense to BUSY at the time of the reception of the packet to a receptionstop time is converted into a slot time and is subtracted from a backoffcounter. Thus, it is possible to obtain an operational effect in which,when the second condition is satisfied after the stop of the receptionof the packet, the control is performed such that a time length from atransition time of the carrier sense to BUSY at the time of thereception of the packet to a reception stop time is converted into aslot time and is subtracted from a backoff counter.

In the first aspect, when a result after the subtraction is a negativevalue, the control unit may treat the result as 0. Thus, it is possibleto obtain an operational effect in which, when the result after thesubtraction is the negative value, the result is treated as 0.

In the first aspect, when a result after the subtraction is a negativevalue, the control unit may set a value obtained by returning the resultto a positive value corresponding to the negative value so that thevalue does not exceed the backoff counter before the subtraction. Thus,it is possible to obtain an operational effect in which, when the resultafter the subtraction is the negative value, the value obtained byreturning the result positively to the value corresponding to thenegative value is set so that the value does not exceed the backoffcounter before the subtraction.

In the first aspect, the first condition may include a condition that aCRC calculation result obtained when a physical header of the packetduring the reception is a target not be identical to CRC informationdescribed in the physical header. Thus, it is possible to obtain anoperational effect in which the condition that the CRC calculationresult obtained when the physical header of the packet during thereception is the target not be identical to the CRC informationdescribed in the physical header is set as the first condition.

In the first aspect, when information regarding an identifier foridentifying a network is present in the physical header of the packet,the first condition may further include a condition that the informationregarding the identifier be different from a network identifier of anetwork to which the information processing device belongs. Thus, it ispossible to obtain an operational effect in which, when the informationregarding the identifier for identifying the network is present in thephysical header of the packet, the condition that the informationregarding the identifier be different from the network identifier of thenetwork to which the self-device belongs is set as the first condition.

In the first aspect, the first condition may further include a conditionthat a preamble correlator output level of the packet during thereception in antenna input conversion be less than a threshold derivedfrom information described in the physical header of the packet. Thus,it is possible to obtain an operational effect in which the conditionthat the preamble correlator output level of the packet during thereception in the antenna input conversion be less than the thresholdderived from information described in the physical header of the packetis set as the first condition.

In the first aspect, when information regarding an identifier foridentifying a network is present in the physical header of the packetand the information regarding the identifier is identical to a networkidentifier of a network to which the information processing devicebelongs, the control unit may continue the reception without stoppingthe reception. Thus, it is possible to obtain an operational effect inwhich, when the information regarding the identifier for identifying thenetwork is present in the physical header of the packet and theinformation regarding the identifier is identical to the networkidentifier of the network to which the self-device belongs, thereception is continued without stopping the reception.

In the first aspect, the control unit may perform the derivation basedon matching between an index described in the physical header of thepacket and a table of thresholds shared in advance. Thus, it is possibleto obtain an operational effect in which the derivation is performedbased on the matching between the index described in the physical headerof the packet and the table of thresholds shared in advance.

In the first aspect, the control unit may perform the derivation throughconversion based on a value described in the physical header of thepacket and information regarding a unit and quantization shared inadvance. Thus, it is possible to obtain an operational effect in whichthe derivation is performed through the conversion based on the valuedescribed in the physical header and the information regarding the unitand the quantization shared in advance.

In the first aspect, the second condition may include the firstcondition. Thus, it is possible to obtain an operational effect in whichthe second condition including the first condition is used.

In the first aspect, the control unit may determine necessity andnon-necessity of the operation using a condition that reception power ofthe packet during the reception be less than a pre-decided energydetection threshold, as the second condition. Thus, it is possible toobtain an operational effect in which the condition that reception powerof the packet during the reception be less than the pre-decided energydetection threshold is set as the second condition.

In the first aspect, the control unit may determine necessity andnon-necessity of the operation using a condition that transmissionsuppression by virtual carrier sense not be applied at the time ofstopping of the reception of the packet, as the second condition. Thus,it is possible to obtain an operational effect in which the conditionthat the transmission suppression by the virtual carrier sense not beapplied at the time of stopping of the reception of the packet is set asthe second condition.

In the first aspect, the control unit may determine necessity andnon-necessity of the operation using a condition that a CRC calculationresult obtained when a physical header of the packet is a target not beidentical to CRC information described in the physical header and apreamble correlator output level of the packet in antenna inputconversion be less than a minimum packet detection threshold amongapplicable packet detection thresholds, as the second condition. Thus,it is possible to obtain an operational effect in which the necessityand non-necessity of the operation is determined using, as the secondcondition, the condition that the CRC calculation result obtained whenthe physical header of the packet is the target not be identical to theCRC information described in the physical header and the preamblecorrelator output level be less than the minimum packet detectionthreshold among the applicable packet detection thresholds.

In the first aspect, when the second condition is not satisfied afterstop of the reception of the packet, the control unit may performcontrol such that transmission from the information processing deviceduring a continuity period of the packet transfer is prohibited. Thus,it is possible to obtain an operational effect in which, when the secondcondition is not satisfied after the stop of the reception of thepacket, the transmission from the information processing device during acontinuity period of the packet transfer is prohibited.

In the first aspect, when the second condition is not satisfied afterthe stop of the reception of the packet and the transmission from theinformation processing device during the continuity period of the packettransfer is prohibited, the control unit performs control such that areply to a frame which is destined for the information processing deviceand requests the reply is transmitted when the frame is received. Thus,it is possible to obtain an operational effect in which, when the secondcondition is not satisfied after the stop of the reception of the packetand the transmission from the self-device during the continuity periodof the packet transfer is prohibited, the reply to the frame which isdestined for the self-device and requests the reply is transmitted whenthe frame is received.

Advantageous Effects of Invention

According to the present technology, it is possible to obtain theadvantageous effect in which radio resources can be efficiently used.Note that the advantageous effects described above are not necessarilylimitative, and the advantageous effects described in the presentdisclosure may be achieved.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram showing a system configuration example of acommunication system 10 according to a first embodiment of the presenttechnology.

FIG. 2 is a diagram showing a system configuration example of thecommunication system 10 according to the first embodiment of the presenttechnology.

FIG. 3 is a diagram showing a system configuration example of thecommunication system 10 according to the first embodiment of the presenttechnology.

FIG. 4 is a diagram showing an example of a transmission and receptionprocess by information processing devices included in the communicationsystem 10 in a time series manner according to the first embodiment ofthe present technology.

FIG. 5 is a block diagram showing a functional configuration example ofan information processing device 100 according to the first embodimentof the present technology.

FIG. 6 is a sequence chart showing a communication processing examplebetween devices included in the communication system 10 according to thefirst embodiment of the present technology.

FIG. 7 is a diagram showing an example of the format of a PPDU exchangedbetween the devices included in the communication system 10 according tothe first embodiment of the present technology.

FIG. 8 is a sequence chart showing an example of a connection processbetween the devices included in the communication system 10 according tothe first embodiment of the present technology.

FIG. 9 is a diagram schematically showing an example of content of asetting information list 161 stored in a memory of an informationprocessing device 200 according to the first embodiment of the presenttechnology.

FIG. 10 is a flowchart showing an example of a processing order of aphysical header parameter decision process by the information processingdevice 200 according to the first embodiment of the present technology.

FIG. 11 is a diagram showing an example of the configuration of acorrelator included in the information processing device 200 accordingto the first embodiment of the present technology.

FIG. 12 is a diagram showing a system configuration example of thecommunication system 10 according to the first embodiment of the presenttechnology.

FIG. 13 is a diagram showing a system configuration example of thecommunication system 10 according to the first embodiment of the presenttechnology.

FIG. 14 is a diagram showing an example of a beacon frame formatexchanged between the devices included in the communication system 10according to the first embodiment of the present technology.

FIG. 15 is a sequence chart showing an example of a physical headerparameter sharing process between the devices included in thecommunication system 10 according to the first embodiment of the presenttechnology.

FIG. 16 is a flowchart showing an example of a processing order of a usephysical header decision process by the information processing device100 according to the first embodiment of the present technology.

FIG. 17 is a flowchart showing an example of a processing order of atransmission and reception process by the information processing device100 according to the first embodiment of the present technology.

FIG. 18 is a flowchart showing a packet detection determination processin the transmission and reception process by the information processingdevice 100 according to the first embodiment of the present technology.

FIG. 19 is a flowchart showing an example of a processing order of thetransmission and reception process by the information processing device100 according to a second embodiment of the present technology.

FIG. 20 is a diagram showing an example of the format of a PPDUexchanged between devices included in a communication system 10according to a third embodiment of the present technology.

FIG. 21 is a diagram showing an example of the format of a PPDUexchanged between devices included in a communication system 10according to a fourth embodiment of the present technology.

FIG. 22 is a flowchart showing a packet detection determination processin the transmission and reception process by the information processingdevice 100 according to the fourth embodiment of the present technology.

FIG. 23 is a diagram showing an example of a beacon frame formatexchanged between devices included in a communication system 10according to a fifth embodiment of the present technology.

FIG. 24 is a sequence chart showing an example of a connection processbetween the devices included in the communication system 10 according tothe fifth embodiment of the present technology.

FIG. 25 is a flowchart showing a packet detection determination processin the transmission and reception process by the information processingdevice 100 according to the fifth embodiment of the present technology.

FIG. 26 is a flowchart showing a packet detection determination processin the transmission and reception process by an information processingdevice 100 according to a sixth embodiment of the present technology.

FIG. 27 is a diagram showing an example of the configuration of acorrelator included in the information processing device 100 accordingto the sixth embodiment of the present technology.

FIG. 28 is a diagram showing a system configuration example of acommunication system 50 according to a seventh embodiment of the presenttechnology.

FIG. 29 is a sequence chart showing a communication processing examplebetween devices included in a communication system 50 according to theseventh embodiment of the present technology.

FIG. 30 is a sequence chart showing a communication processing examplebetween devices included in a communication system 50 according to aneighth embodiment of the present technology.

FIG. 31 is a diagram showing an example of the format of a PPDUexchanged between the devices included in the communication system 10according to a ninth embodiment of the present technology.

FIG. 32 is a diagram showing an example of a beacon frame formatexchanged between the devices included in the communication system 10according to the ninth embodiment of the present technology.

FIG. 33 is a diagram showing the flow of a backoff process in the IEEE802.11 standard.

FIG. 34 is a diagram showing the flow of a backoff process by aninformation processing device 100 according to the ninth embodiment ofthe present technology.

FIG. 35 is a diagram showing the flow of a backoff process by theinformation processing device 100 according to the ninth embodiment ofthe present technology.

FIG. 36 is a flowchart showing an example of a processing order of a usephysical header decision process by the information processing device100 according to the ninth embodiment of the present technology.

FIG. 37 is a flowchart showing an example of a processing order of atransmission and reception process by the information processing device100 according to the ninth embodiment of the present technology.

FIG. 38 is a diagram showing an example of a relation (processclassification table) between a physical header and a process performedby the information processing device 100 according to the ninthembodiment of the present technology.

FIG. 39 is a flowchart showing a packet detection and receptiondetermination process in the transmission and reception process by theinformation processing device 100 according to the ninth embodiment ofthe present technology.

FIG. 40 is a diagram showing an example of the format of a PPDUexchanged between devices included in a communication system 10according to a tenth embodiment of the present technology.

FIG. 41 is a diagram showing an example of a relation (processclassification table) between a physical header and a process performedby an information processing device 100 according to a tenth embodimentof the present technology.

FIG. 42 is a flowchart showing a packet detection and receptiondetermination process in the transmission and reception process by theinformation processing device 100 according to the tenth embodiment ofthe present technology.

FIG. 43 is a diagram showing an example of the format of a PPDUexchanged between devices included in a communication system 10according to an eleventh embodiment of the present technology.

FIG. 44 is a diagram showing an example of a beacon frame formatexchanged between the devices included in the communication system 10according to the eleventh embodiment of the present technology.

FIG. 45 is a flowchart showing an example of a processing order of a usephysical header decision process by the information processing device100 according to the eleventh embodiment of the present technology.

FIG. 46 is a diagram showing an example of a relation (processclassification table) between a physical header and a process performedby the information processing device 100 according to the eleventhembodiment of the present technology.

FIG. 47 is a diagram showing an example of the format of a PPDUexchanged between devices included in a communication system 10according to a twelfth embodiment of the present technology.

FIG. 48 is a flowchart showing an example of a processing order of aphysical header parameter decision process by the information processingdevice 200 according to the twelfth embodiment of the presenttechnology.

FIG. 49 is a diagram showing an example of a beacon frame formatexchanged between the devices included in the communication system 10according to the twelfth embodiment of the present technology.

FIG. 50 is a diagram showing an example of a relation (processclassification table) between a physical header and a process performedby the information processing device 100 according to the twelfthembodiment of the present technology.

FIG. 51 is a block diagram showing an example of a schematicconfiguration of a smartphone.

FIG. 52 is a block diagram showing an example of a schematicconfiguration of a car navigation device.

FIG. 53 is a block diagram showing an example of a schematicconfiguration of a wireless access point.

DESCRIPTION OF EMBODIMENT(S)

Hereinafter, modes for carrying out the present technology (hereinafterreferred to as embodiments) will be described. The description will bemade in the following order.

1. First embodiment (example in which Link Strength Category field isset up in SIGNAL field of IEEE 802.11 standard and packet detectioncondition is set according to information processing device)2. Second embodiment (example in which no transmission is performed whenpacket detection determination result is only-energy detection andtransmission suppression is set)3. Third embodiment (example in which Link Strength Category field isset up in Service field of IEEE 802.11 standard)4. Fourth embodiment (example in which plurality of preamble sequenceswith different detection thresholds are used on transmission side andpreamble correlation detector applied by RSSI is switched on receptionside)5. Fifth embodiment (example in which physical header used bysubordinate information processing device is selected by master stationside)6. Sixth embodiment (example in which plurality of PLCP preambles fordiscrimination are generated by processing part of original sequencerather than completely different sequences)7. Seventh embodiment (example in which direct communication betweenslave stations is performed)8. Eighth embodiment (example in which physical header parameters usedbetween direct links are decided by slave station)9. Ninth embodiment (example in which information regarding identifierof BSS is stored in signal field of IEEE 802.11 standard)10. Tenth embodiment (example in which plurality of preamble sequencesare defined and COLOR information is used together)11. Eleventh embodiment (example in which physical header parameterdecision process is omitted)12. Twelfth embodiment (example in which field storing informationregarding identifier of BSS in SIGNAL field of IEEE 802.11 standard isset up)13. Application examples

1. First Embodiment [Configuration Example of Communication System]

FIG. 1 is a diagram showing a system configuration example of acommunication system 10 according to a first embodiment of the presenttechnology.

The communication system 10 is configured to include informationprocessing devices 100 to 103 and information processing devices 200 and201.

The information processing devices 100 to 103 are, for example, portableinformation processing devices that have a wireless communicationfunction. Here, the portable information processing devices are, forexample, information processing devices such as smartphones, mobilephones, or tablet terminals. The information processing devices 100 to103 are assumed to have a communication function in conformity with, forexample, a wireless local area network (LAN) standard of Institute ofElectrical and Electronic Engineers (IEEE) 802.11. As the wireless LAN,for example, Wireless Fidelity (Wi-Fi), Wi-Fi Direct, or Wi-Fi CERTIFIEDMiracast specification (technical specification name: Wi-Fi Display) canbe used. Wireless communication using another communication scheme maybe used.

The information processing devices 200 and 201 are, for example, fixedinformation processing devices that have a wireless communicationfunction. Here, the fixed information processing devices are, forexample, information processing devices such as access points or basestations. As in the information processing devices 100 to 103, theinformation processing devices 200 and 201 are assumed to have acommunication function in conformity with, for example, a wireless LANstandard of IEEE 802.11. Wireless communication using anothercommunication scheme may be used.

The information processing devices 200 and 201 are assumed to functionas master stations and the information processing devices 100 to 103 areassumed to function as slave stations. That is, in the first embodimentof the present technology, a communication example between master andslave stations in a star type topology configured by the master andsubordinate slave stations will be described. In the first embodiment ofthe present technology, a communication example in which a destinationfor transmission by subordinate slave stations is restricted to a masterstation will be described.

The information processing devices 100 and 102 and the info′ nationprocessing devices 200 and 201 are assumed to have specific functions(specific functions described in each embodiment of the presenttechnology). Conversely, the information processing devices 101 and 103are assumed to have no specific function. In this way, the informationprocessing devices that have no specific function are referred to aslegacy devices. The specific function will be described in eachembodiment of the present technology. The legacy devices can beconfigured as, for example, information processing devices that have acommunication function in conformity with a wireless LAN standard ofIEEE 802.11a, IEEE 802.11g, IEEE 802.11n, or IEEE 802.11ac.

In the first embodiment of the present technology, a communicationexample between the devices when the information processing devices 100and 101 are connected and the information processing devices 201 and 102are connected will be described.

FIG. 1 shows an example in which the communication system 10 isconfigured of four slave stations (the information processing devices100 to 103), but the number of slave stations (the informationprocessing devices) is not limited to 4. That is, an embodiment of thepresent technology can also be applied to a communication systemconfigured of three or five or more slave stations (informationprocessing devices).

In a relation between two information processing devices performingcommunication, one of the information processing devices may serve as amaster slave and the other information processing device may serve as aslave station. Connection between two information processing devices maybe direct communication connection between slave stations.

Here, in an autonomous distributed wireless network, a scheme referredto as carrier sense is generally adopted as an adjustment structure foravoiding packet collision. The carrier sense is a scheme of monitoring anearby wireless situation for a given time and confirming whether thereis another information processing device performing transmission beforeperforming transmission. When reception power equal to or greater than athreshold is detected during the continuation, a wireless state isdetermined to be a busy state, a transmission operation is stopped, andthus the transmission is not performed.

In the carrier sense, there are two kinds of detection algorithms:preamble detection in which detection is performed through powercomparison between correlator outputs of specific preambles and energydetection in which detection is performed through power comparisonbetween received signals. In general, the two kinds of detectionalgorithms are used together. Hereinafter, the two kinds of detectionalgorithms are collectively referred to as the carrier sense in thedescription unless otherwise stated.

As described above, when the number of information processing devices ina network increases, there is a concern of excessive transmissionsuppression and a situation in which transmission efficiency of anentire system deteriorates in the above-described carrier sense scheme.

Here, an example of a positional relation in which such a situationarises will be described with reference to FIG. 1. In FIG. 1, there aretwo master stations (the information processing devices 200 and 201) andfour slave stations (the information processing devices 100 to 103). InFIG. 1, the information processing devices 100 and 101 are connected tothe information processing device 200 and the information processingdevices 102 and 103 are connected to the information processing device201 to perform communication with one another. In FIG. 1, connectionrelations between the devices are schematically indicated by dottedlines.

In FIG. 1, the information processing devices 100 to 103, 200, and 201are assumed to be present in a positional relation in which transmissionof all the information processing devices can be mutually detected bythe carrier sense.

Here, for example, the information processing device 100 is assumed toperform transmission to the information processing device 200 and theinformation processing device 102 is assumed to perform transmission tothe information processing device 201.

[Example of Carrier Sense Detection Range]

FIGS. 2 and 3 are diagrams showing system configuration examples of thecommunication system 10 according to the first embodiment of the presenttechnology. FIGS. 2 and 3 show examples in which carrier sense detectionranges of the information processing devices in the example shown inFIG. 1 overlap.

In FIGS. 2 and 3, carrier sense detection ranges 11 to 16 of theinformation processing devices 100, 102, 200, and 201 are schematicallyindicated by dotted circles.

Specifically, in FIGS. 2 and 3, the carrier sense detection range 11indicates a carrier sense detection range of the information processingdevice 200 and the carrier sense detection range 12 indicates a carriersense detection range of the information processing device 201.

In FIG. 2, the carrier sense detection range 13 indicates a carriersense detection range of the information processing device 100 and thecarrier sense detection range 14 indicates a carrier sense detectionrange of the information processing device 102.

In FIG. 3, the carrier sense detection range 15 indicates a carriersense detection range of the information processing device 100 after thecarrier sense detection range 13 shown in FIG. 2 is changed. The carriersense detection range 16 indicates a carrier sense detection range ofthe information processing device 102 after the carrier sense detectionrange 14 shown in FIG. 2 is changed.

As described above, the carrier sense is an example of the adjustmentstructure for avoiding packet collision and is a scheme of performingtransmission suppression according to whether there is anotherinformation processing device performing transmission. The carrier sensedetection range is decided to correspond to a threshold used at the timeof detection of a signal transmitted from another information processingdevice.

Here, for example, it is assumed that the information processing device100 performs the carrier sense to perform transmission while theinformation processing device 102 performs transmission to theinformation processing device 201. For example, when the informationprocessing device 100 detects the transmission of the informationprocessing device 102, the transmission is suppressed, and thus thetransmission may not be performed until the transmission of theinformation processing device 102 ends.

However, even when the information processing device 100 performs thetransmission to the information processing device 200 during thetransmission by the information processing device 102, the informationprocessing devices 200 and 201 which are reception sides can alsoperform reception according to a ratio between desired waves andinterference waves. The desired waves are radio waves from theinformation processing device 100 to the information processing device200 or radio waves from the information processing device 102 to theinformation processing device 201. The interference waves are radiowaves from the information processing device 100 to the informationprocessing device 201 or radio waves from the information processingdevice 102 to the information processing device 200.

For example, as shown in FIG. 1, reception possibility is assumed to behigher between the information processing devices 102 and 200 when adistance therebetween is greater than a distance between the informationprocessing devices 100 and 200. Accordingly, when collision avoidance isensured and an improvement is potentially achieved, it is important toimprove efficiency of a carrier sense mechanism that suppressestransmission.

For example, as shown in FIG. 3, a case in which carrier sense detectionthresholds of the information processing devices 100 and 102 are changedto be set to be higher so that mutual transmission radio waves are notdetectable will be assumed. In this case, since the informationprocessing device 100 is configured not to detect transmission from theinformation processing device 102, the information processing devices100 and 102 can each simultaneously perform transmission andsimultaneously use radio resources.

However, when an information processing device of a reception side doesnot reliably wait for transmission opportunities despite an increase inthe transmission opportunities of an information processing device on atransmission side, a case in which a gain is not obtained withouttransmission success is assumed. This example is shown in FIG. 4.

FIG. 4 is a diagram showing an example of a transmission and receptionprocess by the information processing devices included in thecommunication system 10 in a time series manner according to the firstembodiment of the present technology.

FIG. 4 shows an example of a case in which the information processingdevice 100 performs transmission to the information processing device200 while the information processing device 102 performs transmission tothe information processing device 201 in the example shown in FIG. 1.

For example, as shown in FIG. 3, the information processing device 102is in the carrier sense detection range 11 of the information processingdevice 200. Therefore, when the information processing device 200 firstdetects transmission (21) of the information processing device 102 andstarts reception of an interference side (22), the informationprocessing device 200 may not receive transmission (23) from theinformation processing device 100 newly obtaining a transmissionopportunity (22). In this way, even when a ratio of signal waves tointerference waves is sufficiently high, there is a concern of receptionfailing.

Accordingly, for example, raising the carrier sense detection thresholdof the information processing device 200 can be considered. However, themaster station has a plurality of subordinate information processingdevices and necessarily waits simultaneously. Therefore, when the masterstation uniformly raises the carrier sense detection threshold, there isa concern that communication with the subordinate information processingdevices from which information is to be received may not beappropriately detected. Therefore, a case in which the carrier sensedetection threshold is changed is preferably restricted only to, forexample, a case in which the change in the carrier sense detectionthreshold is actually necessary or a case in which improvement isreliably expected.

Accordingly, in an embodiment of the present technology, an example inwhich radio resources are appropriately reused when improvement can beachieved while suppressing side effects caused due to the raising of thecarrier sense detection threshold as small as possible will bedescribed. In this case, reception levels of packets transmitted andreceived from a third party can also be set as examination targets.

Specifically, in an embodiment of the present technology, a transmissionside information processing device is configured to change content of aPhysical Layer Convergence Protocol (PLCP) header according tocommunication quality (for example, a propagation attenuation amount)with a destination. A reception side information processing device isconfigured to detect only a desired packet by changing a packetdetection threshold to be applied using a part of the received contentof the PLCP header.

Here, the PLCP is a protocol for transmitting a portion that isnecessary to be commonly received through modulation at a given speedirrespective of a transmission rate and encapsulating a MAC frame totransmit a data portion subsequent to the portion by various methodsaccording to a device and a situation at that time.

For example, a PLCP preamble is used to detect a packet or estimate apropagation path gain. The PLCP header is used to convey informationsuch as the modulation of the data portion or the length of a frame.

[Configuration Example of Information Processing Device]

FIG. 5 is a block diagram showing a functional configuration example ofthe information processing device 100 according to the first embodimentof the present technology. Since functional configurations (functionalconfigurations related to wireless communication) of the informationprocessing devices 101 to 103, 200, and 201 are substantially the sameas those of the information processing device 100, the descriptionthereof will be omitted herein.

The information processing device 100 includes a data processing unit110, a transmission processing unit 120, a modulation and demodulationunit 130, a wireless interface unit 140, an antenna 141, a control unit150, and a memory 160.

The data processing unit 110 processes various kinds of data under thecontrol of the control unit 150. For example, the data processing unit110 generates bodies of various data frames, data packets, and the like.For example, when a transmission operation is performed, the dataprocessing unit 110 generates various data frames and data packets andsupplies the various data frames and data packets to the transmissionprocessing unit 120 in response to a request from an upper layer. Forexample, when a reception operation is performed, the data processingunit 110 processes and analyzes various data frames and data packetssupplied from the transmission processing unit 120.

The transmission processing unit 120 performs various transmissionprocesses under the control of the control unit 150. For example, when atransmission operation is performed, the transmission processing unit120 performs a process such as addition of a header or addition of anerror detection code to a packet generated by the data processing unit110 for media access control. For example, the transmission processingunit 120 performs a process such as addition of a Media Access Control(MAC) header for the MAC or addition of an error detection code to apacket generated by the data processing unit 110. Then, the transmissionprocessing unit 120 supplies the processed data to the modulation anddemodulation unit 130.

When the carrier sense is used, the transmission processing unit 120calculates a Network Allocation Vector (NAV) to be added. Here, asdescribed above, the carrier sense is an example of the adjustmentstructure for packet collision avoidance and is a scheme of describing atransmission suppression time in content of a wireless packet andsetting transmission suppression in an information processing devicereceiving the packet. The NAV is the transmission suppression time.

For example, when a reception operation is performed, the transmissionprocessing unit 120 performs a reverse process (for example, packeterror detection or analysis and removal of a MAC header) to thetransmission operation on a bit stream supplied from the modulation anddemodulation unit 130. Then, when it is confirmed that there is no errorin the data frame based on the error detection code, the transmissionprocessing unit 120 supplies various data frames to the data processingunit 110.

The transmission processing unit 120 performs a virtual carrier senseprocess. In this case, when the NAV is set in the header of the receivedpacket and the transmission suppression is applied, the transmissionprocessing unit 120 notifies the control unit 150 that the NAV is setand the transmission suppression is applied.

The modulation and demodulation unit 130 performs modulation anddemodulation processes under the control of the control unit 150. Forexample, when a transmission operation is performed, the modulation anddemodulation unit 130 performs encoding, interleaving, modulation, andaddition of a PLCP header and a PLCP preamble on the bit stream inputfrom the transmission processing unit 120 based on coding and amodulation scheme set by the control unit 150. Then, the modulation anddemodulation unit 130 generates a data symbol string and supplies thedata symbol string to the wireless interface unit 140.

For example, when a reception operation is performed, the modulation anddemodulation unit 130 performs a reverse process to the transmissionoperation on an input from the wireless interface unit 140 and suppliesthe result to the transmission processing unit 120. The modulation anddemodulation unit 130 performs a carrier sense process. In this case,when reception power equal to or greater than a threshold is detected ora value of preamble correlation equal to or greater than a predeterminedoutput is detected, the modulation and demodulation unit 130 determinesthat a wireless state is a busy state and notifies the control unit 150that the wireless state is the busy state.

The wireless interface unit 140 is an interface that is connected toanother information processing device to transmit and receive variouskinds of information. For example, when a transmission operation isperformed, the wireless interface unit 140 converts an input from themodulation and demodulation unit 130 into an analog signal, performsamplification, filtering, and frequency upconverting, and transmits theresult as a wireless signal from the antenna 141. For example, when areception operation is performed, the wireless interface unit 140performs a reverse process to the transmission operation on an inputfrom the antenna 141 and supplies the result to the modulation anddemodulation unit 130.

The control unit 150 controls reception and transmission operations ofeach of the data processing unit 110, the transmission processing unit120, the modulation and demodulation unit 130, and the wirelessinterface unit 140. For example, the control unit 150 performs deliveryof information between the units, setting of communication parameters,and scheduling of packets in the transmission processing unit 120. Forexample, when the control unit 150 receives notification of carriersense results from the modulation and demodulation unit 130 and thetransmission processing unit 120, the control unit 150 performs eachprocess related to setting of the transmission suppression orcancellation of the setting based on the notification.

For example, a control unit (corresponding to the control unit 150) ofthe information processing device 200 performs control such thatphysical headers (for example, a PLCP preamble and a PLCP header) usedfor packets transmitted by another information processing device aretransmitted to another information processing device using wirelesscommunication.

For example, the control unit 150 performs control such that one headeris selected from a plurality of physical header candidates (for example,PLCP preambles and PLCP headers) and is used for a transmission targetpacket. Here, the plurality of physical header candidates correspond toinformation regarding a plurality of physical headers (for example, PLCPpreambles and PLCP headers) transmitted from the information processingdevice 200.

For example, the control unit of the information processing device 200performs control such that packet detection conditions (for example,detection thresholds of the PLCP preambles) used by another informationprocessing device are transmitted to another information processingdevice using wireless communication.

For example, the control unit 150 performs control such that one packetdetection condition is selected to be used from a plurality of packetdetection conditions (for example, detection thresholds of the PLCPpreambles) in regard to a plurality of packets transmitted from theinformation processing device 200 using wireless communication. Here,the plurality of packet detection conditions correspond to the pluralityof packet detection conditions transmitted from the informationprocessing device 200.

For example, the control unit 150 performs control such that onereception operation is selected to be performed from a plurality ofreception operations in regard to a plurality of packets transmittedfrom the information processing device 200 using wireless communication.The plurality of reception operations will be described according to thefirst to eleventh embodiments of the present technology.

The memory 160 has a role of a working area of data processing by thecontrol unit 150 or a function of a storage medium that retains variouskinds of data. As the memory 160, for example, a storage medium such asa non-volatile memory, a magnetic disk, an optical disc, or amagneto-optical (MO) disc can be used. As the non-volatile memory, forexample, an electrically erasable programmable read-only memory (EEPROM)or an erasable programmable ROM (EPROM) can be used. As the magneticdisk, for example, a hard disk or a discoid magnetic disk can be used.As the optical disc, for example, a compact disc (CD), a digitalversatile disc recordable (DVD-R), or a Blu-Ray Disc (BD: registeredtrademark) can be used.

In each embodiment of the present technology, an example in which eachtransmission succeeds when uplink transmission from the informationprocessing device 100 to the information processing device 200 anduplink transmission from the information processing device 102 to theinformation processing device 201 are performed simultaneously (orsubstantially simultaneously) will be described. An embodiment of thepresent technology can also be applied to transmission between theinformation processing devices other than such transmission.

[Communication Example]

FIG. 6 is a sequence chart showing a communication processing examplebetween the devices included in the communication system 10 according tothe first embodiment of the present technology.

FIG. 6 shows a communication processing example when uplink transmissionfrom the information processing device 100 to the information processingdevice 200 is performed. The same also applies to a relation betweenother information processing devices (for example, the informationprocessing devices 102 and 201).

First, a connection process between the information processing devices100 and 200 is performed (401). The connection process will be describedin detail with reference to FIG. 8.

Subsequently, the information processing device 200 performs a physicalheader parameter decision process (402). The physical header parameterdecision process will be described in detail with reference to FIG. 10.

Subsequently, a physical header parameter sharing process is performedbetween the information processing devices 100 and 200 (403). That is, aprocess of sharing physical header parameters decided through thephysical header parameter decision process between the informationprocessing devices 100 and 200 is performed (403).

Subsequently, the information processing device 200 performs atransmission and reception process (405).

The information processing device 100 performs a use physical headerdecision process (404). The use physical header decision process will bedescribed in detail with reference to FIG. 16. Subsequently, theinformation processing device 100 performs the transmission andreception process (406).

[Example of Format of Presentation-Layer Protocol Data Unit (PPDU)]

FIG. 7 is a diagram showing an example of the format of a PPDU exchangedbetween the devices included in the communication system 10 according tothe first embodiment of the present technology.

The PPDU is configured to include Preamble 301, SIGNAL 302, Extension303, Service 304, MAC Protocol Data Unit (MPDU) 305, and Frame CheckSequence (FCS) 306.

The Preamble 301 indicates a portion corresponding to an IEEE 802.11Legacy Short Training Field (L-STF) or Legacy Long Training Field(L-LTF) shown in c of FIG. 7. The Preamble 301 is assumed to have aformat compatible with this field.

The SIGNAL 302 indicates an WEE 802.11 Legacy SIGNAL (L-SIG) or HighThroughput SIGNAL (HT-SIG) field shown in c of FIG. 7. HT Mixed ModeFormat of IEEE 802.11n is shown as an example in c of FIG. 7. The HT-SIGmay be replaced with a Very High Throughput SIGNAL-A (VHT-SIG-A) fieldin IEEE 802.11ac and with High Efficiency SIGNAL (HE-SIG) field in IEEE802.11ax.

In accordance with a format, additional fields (HT-STF, HT-LTF, VHT-STF,VHT-LTF, and VHT-SIG-B) are attached subsequently in some cases.

Here, in the first embodiment of the present technology, “Link StrengthCategory field” is newly prepared in a part of the field of the SIGNAL302 which is a PLCP header of the physical header. That is, “LinkStrength Category field” is newly set up in a portion treated as beingreserved in the SIGNAL 302 of the PLCP header. Each informationprocessing device (other than a legacy device) changes “Link StrengthCategory field” according to the quality of a link with a designation atthe time of transmission.

An example in which 1 is stored in “Link Strength Category field” isshown in a of FIG. 7. An example in which 0 is stored in “Link StrengthCategory field” is shown in b of FIG. 7. In this way, the examples inwhich the value (0 or 1) of two stages is stored in “Link StrengthCategory field” are shown in a and b of FIG. 7, but a value of 3 or morestages may be stored.

In this way, in the first embodiment of the present technology, “LinkStrength Category field” is set up a portion treated as being reservedin the SIGNAL 302. Thus, it is possible to realize a specific functionin the first embodiment of the present technology without interferingwith reception of the legacy device.

In the first embodiment of the present technology, a physical header ofLink Strength Category field=0 is referred to as “long-distance physicalheader.” Further, a physical header of Link Strength Category field=1 isreferred to as “short-distance physical header.” A physical headertransmitted from a legacy device is assumed to be treated as a“long-distance physical header.”

An information processing device (other than a legacy device) receivinga packet including Link Strength Category field changes a detectionthreshold to be applied according to content (0 or 1) of Link StrengthCategory field.

[Example of Connection Process]

FIG. 8 is a sequence chart showing an example of a connection processbetween the devices included in the communication system 10 according tothe first embodiment of the present technology.

FIG. 8 shows a processing example until connection between theinformation processing devices 100 and 200 is established. The same alsoapplies to a relation between the information processing devices 102 and201.

When connection is attempted, link quality between the informationprocessing devices 100 and 200 is unknown. For this reason, to reliablyperform connection, the information processing device 100 uses the samepreamble detection threshold and physical header as those of the legacydevice without performing adjustment of the threshold.

That is, the information processing device 100 sets the same value asthat of a legacy operation (an operation of the legacy device) as thepreamble detection threshold (411). The information processing device100 sets the same format as that of a legacy operation (an operation ofthe legacy device) as the format of the physical header (412).

The information processing device 200 sets the same format as that of alegacy operation (an operation of the legacy device) as the format ofthe physical header (413).

Subsequently, scanning is performed (414), Authentication is performed(415), Association is performed (416), and 4-way Handshake is performed(417).

When the connection is established in this way, the control unit of theinformation processing device 200 generates a list (setting informationlist) of the setting information used by each information processingdevice (for example, the information processing devices (subordinateterminals) connected to the information processing device 200). Thesetting information list is a list that is formed by a combination ofeach detection threshold of the physical header and an application level(application condition) of the physical header used by each informationprocessing device. The setting information list will be described indetail with reference to FIG. 9.

In the embodiment of the present technology, a pair of the detectionthreshold of the physical header and the application level of thephysical header is referred to as a physical header parameter.

The information processing device 200 updates content of informationalready generated in information included in the setting informationlist.

[Example of Content of Setting Information List]

FIG. 9 is a diagram schematically showing an example of content of asetting information list 161 stored in the memory (corresponding to thememory 160 shown in FIG. 5) of an information processing device 200according to the first embodiment of the present technology.

In the setting information list 161, an index 162, a detection threshold163, and an application level 164 are stored in association therewith.

A value (0 or 1) indicating far or near is stored in the index 162.

The detection threshold of the physical header decided through thephysical header parameter decision process is stored in the detectionthreshold 163. The physical header parameter decision process is shownin FIG. 10.

The application level of the physical header decided through thephysical header parameter decision process is stored in the applicationlevel 164.

[Operation Example of Physical Header Parameter Decision Process]

FIG. 10 is a flowchart showing an example of a processing order of aphysical header parameter decision process by the information processingdevice 200 according to the first embodiment of the present technology.

First, the control unit of the information processing device 200performs tentative decision of the physical header parameter used by thesubordinate terminals in a self-basic service set (BSS) and theself-device. The control unit of the information processing device 200tentatively decides a detection threshold PD_near of the short-distancephysical header and a detection threshold PD_far of the long-distancephysical header.

Here, since there is no physical header of the application conditionbelow the detection threshold PD_far of the long-distance physicalheader, a setting value PD_default for the legacy device is tentativelyset as the detection threshold.

The setting value PD_default for the legacy device is a value indicatinga reference level of the preamble detection used by the legacy device.In the IEEE 802.11 standard, as a standard value, a value such as −82dBm every 20 MHz bandwidth is referred to. As the setting valuePD_default for the legacy device, a value other than −82 dBm may beused.

Subsequently, the control unit of the information processing device 200decides application levels L_near and L_far of the physical headersbased on the detection threshold PD_near of the short-distance physicalheader and the detection threshold PD_far of the long-distance physicalheader. Specifically, the control unit of the information processingdevice 200 decides the application levels L_near and L_far of thephysical headers so that the following Expressions 1 and 2 aresatisfied. Here, Expressions 1 and 2 are descriptions in whichcalculation in logarithm (dB) is assumed.

L_near>PD_near+O_near  Expression 1

L_far=−∞  Expression 2

Here, the application levels L_near and L_far of the physical headersare thresholds used to select physical headers (a long-distance physicalheader and a short-distance physical header) to be used based on andcommunication quality with a destination device. For example, when theinformation processing device 100 performs transmission, the applicationlevels L_near and L_far of the physical headers are used as thresholdsat the time of selection of the physical headers to be used as thecommunication quality with the destination device.

In Expression 1, O_near is an offset amount of a margin for a preambledetection error by a variation in a reception level. For example, avalue of about 10 dBm to 20 dBm can be used as O_near. Further, a valueother than 10 dBm to 20 dBm may be used as O_near.

As indicated in Expression 2, L_far is set to the infinitesimal sincethere is no physical header of the application condition below L_far.

Subsequently, the control unit of the information processing device 200performs packet monitoring (step S701). Then, the control unit of theinformation processing device 200 acquires information regardingcommunication quality with each subordinate information processingdevice in the self-BSS and information regarding communication qualityof packets from other BSSs (OBSSs) (step S701).

Here, an example in which correlation output strength of the PLCPpreamble is used as an index of the communication quality will bedescribed. The correlation output strength is not a correlator output inwhich power is normalized, but is assumed to indicate an absolute levelobtained by multiplying a correlator output by a received signalstrength indicator (RSSI). That is, the correlation output strength is acorrelator output corrected to an antenna input conversion. When thereis a reception history at a relatively close time, a record of thecorrelation output strength at that time may be properly used. At thetime of monitoring, the detection threshold may be temporarily loweredso that a more reliable sample is collected.

Here, a relation between the RSSI and a correlation output strength COL(Correlator Output Level) can be simply indicated by the followingexpression.

correlation output strength COL=RSSI×normalized correlator output

An example of the configuration of a correlator is shown in FIG. 11.

[Example of Configuration of Correlator]

FIG. 11 is a diagram showing an example of the configuration of acorrelator included in the information processing device 200 accordingto the first embodiment of the present technology. FIG. 11 shows anexample of the configuration of a general correlator serving as areference. Here, an operator (*) described in FIG. 11 indicates complexconjugate calculation.

Here, for the correlator, in general, there are largely twoconfigurations according to the characteristics of the preamble. Forexample, there are two configurations, a configuration ofautocorrelation detection for generally detecting a signal with certainperiodicity and a configuration of cross-correlation detection fordetecting correlation with a decided pattern. An example of theconfiguration of the autocorrelation detection is shown in a of FIG. 11and an example of the configuration of the cross-correlation detectionis shown in b of FIG. 11.

In FIG. 10, the control unit of the information processing device 200classifies information regarding the communication quality according to“Link Strength Category field” in the physical header used at the timeof reception (step S702).

For example, the control unit of the information processing device 200sets a minimum correlation output strength to COL_self_far in a packetin which the BSS identifier (BSSID) is the self-BSS and a physicalheader is a long-distance physical header and there is no error.

The control unit of the information processing device 200 sets a maximumcorrelation output strength to COL_other_near in a packet in which theBSS identifier (BSSID) is the self-BSS and a physical header is ashort-distance physical header and there is no error.

The control unit of the information processing device 200 sets a maximumcorrelation output strength to COL_other_far in a packet in which theBSS identifier (BSSID) is the self-BSS and a physical header is along-distance physical header and there is no error. COL for which thereis no packet sample of a corresponding condition is assumed to bereplaced with PD_default.

Subsequently, the control unit of the information processing device 200decides the detection threshold PD_near of the short-distance physicalheader and the detection threshold PD_far of the long-distance physicalheader (step S703). That is, the control unit of the informationprocessing device 200 corrects the tentatively decided detectionthreshold PD_near of the short-distance physical header and thetentatively decided detection threshold PD_far of the long-distancephysical header so that relations of the following Expressions 3 to 5are established (step S703).

PD_near>COL_other_near  Expression 3

PD_far<COL_self_far  Expression 4

PD_far>COL_other_far  Expression 5

When there is no PD_far for which Expressions 4 and 5 are compatible,PD_far is decided so that Expression 4 is preferentially established.

When these detection thresholds are decided (updated), the control unitof the information processing device 200 corrects the application levelsL_near and L_far of the physical headers based on the above-describedExpressions 1 and 2 (step S703).

In this way, the detection threshold PD_near of the short-distancephysical header, the detection threshold PD_far of the long-distancephysical header, and the application levels L_near and L_far of thephysical headers are decided. The control unit of the informationprocessing device 200 stores the values decided in this way in thesetting information list 161 (shown in FIG. 9) and refers to thesubsequent values for use for itself. Specifically, the control unit ofthe information processing device 200 stores PD_far in the detectionthreshold 163 corresponding to “0” of the index 162 and stores L_far inthe application level 164 corresponding to “0” of the index 162. Thecontrol unit of the information processing device 200 stores PD_near inthe detection threshold 163 corresponding to “1” of the index 162 andstores L_near in the application level 164 corresponding to “1” of theindex 162.

Here, the monitoring of the nearby packets and the updating of thesetting values described above may be performed periodically oraperiodically. For example, the monitoring and the updating may beperformed periodically every given time or may be performed wheneverconnection of a new subordinate terminal starts.

[Example of Carrier Sense Detection Range]

FIGS. 12 and 13 are diagrams showing system configuration examples ofthe communication system 10 according to the first embodiment of thepresent technology.

FIGS. 12 and 13 show examples of the carrier sense detection ranges ofthe information processing devices set based on the detection thresholdPD_near of the short-distance physical header and the detectionthreshold PD_far of the long-distance physical header decided by theinformation processing device 200.

In FIG. 12, carrier sense detection ranges 31 to 34 of the informationprocessing devices 100 and 102 are schematically indicated by dottedcircles. In FIG. 13, carrier sense detection ranges 41 to 44 of theinformation processing devices 200 and 201 are schematically indicatedby dotted circles.

Specifically, in FIG. 12, the carrier sense detection range 31 indicatesthe carrier sense detection range of the information processing device100 set based on the detection threshold PD_far of the long-distancephysical header. The carrier sense detection range 33 indicates thecarrier sense detection range of the information processing device 100set based on the detection threshold PD_near of the short-distancephysical header.

In FIG. 12, the carrier sense detection range 32 indicates the carriersense detection range of the information processing device 102 set basedon the detection threshold PD_far of the long-distance physical header.The carrier sense detection range 34 indicates the carrier sensedetection range of the information processing device 102 set based onthe detection threshold PD_near of the short-distance physical header.

In FIG. 13, the carrier sense detection range 41 indicates the carriersense detection range of the information processing device 200 set basedon the detection threshold PD_far of the long-distance physical header.The carrier sense detection range 43 indicates the carrier sensedetection range of the information processing device 200 set based onthe detection threshold PD_near of the short-distance physical header.

In FIG. 13, the carrier sense detection range 42 indicates the carriersense detection range of the information processing device 201 set basedon the detection threshold PD_far of the long-distance physical header.The carrier sense detection range 44 indicates the carrier sensedetection range of the information processing device 201 set based onthe detection threshold PD_near of the short-distance physical header.

The examples in which the classification of two values of the shortdistance and the long distance is performed have been described above,but classification of three or more values (N values) may be performed.For example, detection thresholds of the physical headers are set toPD_0, PD_1, . . . , and PD_N and the application levels of the PLCPs areset to L_0, L_1, . . . , and L_N in order for the long distance.Further, the detection thresholds of the physical headers and offsetamounts between the application levels of the physical headers are setto O_0, O_1, . . . , and O_N. In this case, values are decided so thatthe following relation expressions (Expressions 6 to 9) are satisfied.Here, Expressions 6 to 9 are description in which calculation inlogarithm (dB) is assumed.

PD_n>COL_other_n  Expression 6

(where n=0 to N)

PD_0<COL_self_0  Expression 7

L_n>PD_n+O_n  Expression 8

(where n=1 to N)

L_0=−∞  Expression 9

In the case of the classification of three or more values, PD_0 isdecided so that Expression 7 is preferentially established when there isno PD_0 for which Expressions 6 and 7 are compatible.

[Example of Beacon Frame Format]

FIG. 14 is a diagram showing an example of a beacon frame formatexchanged between the devices included in the communication system 10according to the first embodiment of the present technology. Here, anexample of a beacon frame transmitted from the information processingdevice 200 to another information processing device will be described.

FIG. 14 shows an example in which an element such as “Multi DetectParameter” 311 is newly added to a payload 310. In “Multi DetectParameter” 311, an index (0 or 1) indicating far or near is stored in“PLCP Header Indexes” 313 and 316. The detection threshold PD_far of thelong-distance physical header and the detection threshold PD_near of theshort-distance physical header are stored in “Preamble DetectionThresholds” 314 and 317. The application levels of the physical headersare stored in “Apply Levels” 315 and 318.

Generated combinations are set up as combinations of “PLCP HeaderIndex,” “Preamble Detection Threshold,” and “Apply Level.” For example,as shown in FIG. 9, a case in which two pairs of pieces of information(two pairs of “0” and “1” of the index 162) are stored in the settinginformation list 161 will be assumed. In this case, two pairs ofcombinations are set up as combinations of “PLCP Header Index,”“Preamble Detection Threshold,” and “Apply Level.”

Specifically, the control unit of the information processing device 200stores each piece of content of the setting information list 161 shownin FIG. 9 in the beacon frame to transmit the content. That is, thecontrol unit of the information processing device 200 stores informationstored in association with “0” of the index 162 in a first combination(“PLCP Header Index” 313 to “Apply Level” 315). The control unit of theinformation processing device 200 stores information stored inassociation with “1” of the index 162 in a subsequent combination (“PLCPHeader Index” 316 to “Apply Level” 318).

Then, the control unit of the information processing device 200transmits a beacon in which each piece of information indicated in“Multi Detect Parameter” 311 is stored to nearby information processingdevices to inform the nearby information processing devices of thebeacon. That is, the control unit of the information processing device200 transmits the information regarding the packet detection condition(for example, a packet detection threshold (the detection threshold 163shown in FIG. 9) and a selection condition (the application level 164shown in FIG. 9) for selecting the packet detection threshold) to nearbyinformation processing devices to inform the nearby informationprocessing devices of the information. The selection condition can beascertained as a selection condition for selecting one physical headerfrom a plurality of physical header candidates and a selection conditionof the physical header corresponding to each packet detection condition.

[Communication Example of Physical Header Parameter Sharing Process]

FIG. 15 is a sequence chart showing an example of a physical headerparameter sharing process between the devices included in thecommunication system 10 according to the first embodiment of the presenttechnology.

FIG. 15 shows an example of a sharing process in which the control unit150 of the information processing device 100 receives a beacontransmitted from the information processing device 200 and shares thephysical header parameters. The same also applies to a case in whichother information processing devices receive a beacon transmitted fromthe information processing device 200. For example, the control unit ofthe information processing device 200 can notify the subordinateterminal of the physical header parameters using the beacon frame shownin FIG. 14.

First, the control unit of the information processing device 200 storesa set of the detection threshold of each physical header, and theapplication level of each physical header and the index of each physicalheader in the beacon (421). Then, the control unit of the informationprocessing device 200 transmits the beacon to the subordinateinformation processing devices (422 and 423).

When the beacon from the control unit of the information processingdevice 200 is received (423), the control unit 150 of the informationprocessing device 100 acquires and retains the content of “Multi DetectParameter” 311 (shown in FIG. 14) included in the beacon (424).

When the content of “Multi Detect Parameter” 311 included in thesubsequent beacon is changed, the control unit 150 of the informationprocessing device 100 adopts and retains new information after thechange in the content. That is, the old information is updated.

When the content of “Multi Detect Parameter” 311 is already acquired andretained, the control unit 150 of the information processing device 100updates the retained content based on a newly received beacon (424).

The example in which the control unit of the information processingdevice 200 notifies each information processing device of the physicalheader parameters using the beacon has been described FIG. 15, but thephysical header parameters may be notified of using a signal other thanthe beacon. For example, the control unit of the information processingdevice 200 may perform the notification using a unicast data frame ormanagement frame to a subordinate terminal using determination by theself-device or an information acquisition request from the subordinateterminal as a trigger. In this case, the control unit 150 of theinformation processing device 100 similarly acquires and retains thecontent of “Multi Detect Parameter” included in the unicast frame.

[Operation Example of Use Physical Header Decision Process]

FIG. 16 is a flowchart showing an example of a processing order of a usephysical header decision process (transmission physical header selectionprocess) by the information processing device 100 according to the firstembodiment of the present technology.

First, the control unit 150 of the information processing device 100monitors packets received from designations connected to the self-deviceand acquires the RSSI of each designation (step S711). The RSSI(monitoring result) acquired in this way is set to RSSI_peer.

When measured values of the packets received from the destinationsconnected to the self-device are retained, the control unit 150 of theinformation processing device 100 may read the measured value to acquirethe RSSI of each destination (step S711).

Here, in the case of the information processing device (for example, theinformation processing device 100) connected to the master station (forexample, the information processing device 200), only the master stationis basically set as the destination. In this case, the reception levelof a previous beacon may be used as a monitoring result.

Subsequently, the control unit 150 of the information processing device100 compares the acquired RSSI_peer to the application level L_near ofthe physical header and decides the index of the physical header to beused for transmission by the self-device based on the comparison result(step S712). The application level L_near of the physical header isincluded in the beacon transmitted from the information processingdevice 200.

For example, when the acquired RSSI_peer is greater than the applicationlevel L_near of the physical header, the control unit 150 of theinformation processing device 100 decides 1 (for the short distance) asthe index of the physical header to be used for transmission by theself-device (step S712). Conversely, when the acquired RSSI_peer isequal to or less than the application level L_near of the physicalheader, the control unit 150 of the information processing device 100decides 0 (for the long distance) as the index of the physical header tobe used for transmission by the self-device (step S712).

When the index of the physical header to be used for transmission by theself-device is already decided and a new index is decided, the alreadydecided index is updated to the new index (step S712).

In FIG. 16, the example in which the use physical header is decidedbased on the classification of two values of the short distance and thelong distance has been described, but the use physical header may bedecided based on classification of three or more values (N values). Forexample, the application levels of the PLCPs are set to L_0, L_1, . . ., L_N in order for the long distance. In this case, n satisfying thefollowing relation expression (Expression 10) is selected as the indexof the physical header to be used for transmission. Here, Expression 10is description in which calculation in logarithm (dB) is assumed.

L_n≦RSSI_peer<L_n+1  Expression 10

(where n=0 to N)

The operation example of the slave station side in the case of uplinktransmission from the slave station side to the master station side hasbeen described with reference to FIG. 16. In the case of downlinktransmission, however, the same operation may be performed on the masterstation side.

The example in which the RSSI is used has been described in FIG. 16.However, the correlation output strength COL may be used instead of theRSSI.

[Operation Example of Transmission and Reception Process]

FIG. 17 is a flowchart showing an example of a processing order of atransmission and reception process by the information processing device100 according to the first embodiment of the present technology. In FIG.17, the information processing device 100 will be described, but thesame can also apply to the other information processing devices (forexample, the information processing device 200). That is, thetransmission and reception process is the same on both of the masterstation side and the terminal side.

The control unit 150 of the information processing device 100 performs apacket detection determination process for a time other than duringtransmission and during reception (step S730). The packet detectiondetermination process will be described in detail with reference to FIG.18.

Subsequently, the control unit 150 of the information processing device100 determines whether a determination result obtained in the packetdetection determination process is “detection” (step S721). When thedetermination result obtained in the packet detection determinationprocess is “detection” (step S721), the control unit 150 of theinformation processing device 100 performs a reception process ofcontinuing reception (step S722). Then, after the reception iscompleted, the control unit 150 of the information processing device 100returns to a waiting state. When the received packet is destined for theself-device and an instant reply is requested, the control unit 150 ofthe information processing device 100 adds and transmits a physicalheader including the same “Link Strength Category” field as a targetpacket. That is, portions in the SIGNAL field in which the informationregarding the detection thresholds is stored are set to be the same, andinformation decided in the self-device is stored in other portions (forexample, Modulation and Coding Scheme (MCS) and length).

When the determination result obtained in the packet detectiondetermination process is not “detection” (step S721), the control unit150 of the information processing device 100 determines whether thedetermination result obtained in the packet detection determinationprocess is “non-detection” (step S723). When the determination resultobtained in the packet detection determination process is“non-detection” (step S723), the control unit 150 of the informationprocessing device 100 determines whether there is a packet to betransmitted (step S724).

When there is a packet to be transmitted, the control unit 150 of theinformation processing device 100 determines whether a determinationstate of the non-detection continues for an inter frame space (IFS) anda backoff time or more as defined in the procedure of Carrier SenseMultiple Access with Collision Avoidance (CSMA/CA) (step S725).

When the determination state of the non-detection continues for the IFSand the backoff time or more (step S725), the control unit 150 of theinformation processing device 100 performs a transmission process sincetransmission can be performed (step S726). In the transmission process,for example, the control unit 150 of the information processing device100 uses the physical header with the format of the PPDU shown in FIG. 7for the transmission based on the index of the physical header decidedin the transmission physical header decision process shown in FIG. 16.

Specifically, when 1 (for the short distance) is decided as the index inthe transmission physical header decision process, the control unit 150of the information processing device 100 stores 1 in the “Link StrengthCategory field” to perform the transmission (step S726). Conversely,when 0 (for the long distance) is decided as the index in thetransmission physical header decision process, the control unit 150 ofthe information processing device 100 stores 0 in “Link StrengthCategory field” to perform the transmission (step S726).

For example, the control unit 150 of the information processing device100 selects a modulation and communication path coding scheme by which adestination device can perform reception at a high probability accordingto the detection threshold corresponding to the decided physical headerfor the purpose of modulation used in a data portion, and performs thetransmission using the selected scheme. For example, the control unit150 of the information processing device 100 may select a modulation andcommunication path coding scheme (MCS (Modulation and Coding Scheme)) bywhich a destination device can perform reception at a high probabilityaccording to the detection threshold corresponding to the decidedphysical header and perform the transmission. When there is no packet tobe transmitted, the state returns to the waiting state.

When the determination result obtained in the packet detectiondetermination process is not “non-detection” (when the determinationresult is “only-energy detection”) (step S723), the control unit 150 ofthe information processing device 100 basically treats a wireless stateas a busy state and suppresses transmission from the self-device (stepS727). Here, the control unit 150 of the information processing device100 performs the transmission of the reply packet (step S729) only whenthe packet destined for the self-device is received and a replyimmediately after the reception is requested (step S728).

FIG. 18 is a flowchart showing a packet detection determination process(the processing order of step S730 shown in FIG. 17) in the transmissionand reception process by the information processing device 100 accordingto the first embodiment of the present technology.

First, the control unit 150 of the information processing device 100performs measurement of the RSSI on a signal input via the antenna 141and retains the RSSI obtained through the measurement (step S731).

Subsequently, the control unit 150 of the information processing device100 performs correlation calculation of a Preamble pattern to obtain acorrelator output (step S732). The correlator output is theabove-described correlation output strength COL. That is, the correlatoroutput is not a normalized correlator output level, but is a correlatoroutput converted by reflecting reception power.

Subsequently, the control unit 150 of the information processing device100 compares the value of the correlator output to a tentative detectionthreshold to determine whether the value of the correlator output isgreater than the tentative detection threshold (step S733). Here, thetentative detection is detection performed to determine whether to readthe SIGNAL field before the detection determination. The tentativedetection value is set to a value that is equal to or less than both ofPD_near and PD_far described above. The tentative detection thresholdmay be set to PD_default described above.

When the value of the correlator output is greater than the tentativedetection threshold (step S733), the control unit 150 of the informationprocessing device 100 determines that the state is the tentativedetection state (step S734). Subsequently, the control unit 150 of theinformation processing device 100 reads “Link Strength Category field”in the subsequent SIGNAL field of the physical header. As describedabove, information indicating the detection threshold to be applied isstored in “Link Strength Category field.”

Here, the control unit 150 of the information processing device 100retains the content of “Preamble Detection Threshold” shared in thephysical header parameter sharing process shown in FIG. 15. The controlunit 150 of the information processing device 100 decides the detectionthreshold to be applied (an application detection threshold) based onthe content of “Preamble Detection Threshold” and the content of “LinkStrength Category field” (step S735).

For example, in the case of Link Strength Category=0, the control unit150 of the information processing device 100 decides PD_far as theapplication detection threshold. Conversely, in the case of LinkStrength Category=1, the control unit 150 of the information processingdevice 100 decides PD_near as the application detection threshold. Whenthe transmission and reception process is performed, the control unit150 of the information processing device 100 uses the decidedapplication detection threshold (PD_far or PD_near).

Subsequently, the control unit 150 of the information processing device100 compares the measured and retained RSSI to the decided applicationdetection threshold to determine whether the RSSI is greater than theapplication detection threshold (PD_far or PD_near) (step S736). Whenthe RSSI is greater than the application detection threshold (stepS736), the control unit 150 of the information processing device 100sets the packet detection determination result as “detection” (stepS737).

Here, the packet detection determination result may be set to“detection” only when another condition is satisfied. For example, anerror detection code including “Link Strength Category field” as atarget may be set up in a reserved field remaining in the SIGNAL field.A condition that validity of the content of “Link Strength Categoryfield” be confirmed by the error detection code including “Link StrengthCategory field” as the target may be set as an additional determinationcondition.

Here, the error detection code including “Link Strength Category field”as the target may be inserted into a reserved field remaining in theservice field. A condition that validity of the content of “LinkStrength Category field” be confirmed by the error detection codeincluding “Link Strength Category field” as the target may be set as anadditional determination condition.

Conversely, when the RSSI is equal to or less than the applicationdetection threshold (step S736), the control unit 150 of the informationprocessing device 100 interrupts the reception (step S738).Subsequently, the control unit 150 of the information processing device100 compares the RSSI to an energy detection threshold ED to determinewhether the RSSI is greater than the energy detection threshold ED (stepS739). Here, for example, the energy detection threshold ED can be setto −62 dBm every 20 MHz bandwidth.

When the RSSI is greater than the energy detection threshold ED (stepS739), the control unit 150 of the information processing device 100sets the packet detection determination result to “only-energydetection” (step S740).

When the RSSI is equal to or less than the energy detection threshold ED(step S739), the control unit 150 of the information processing device100 sets the packet detection determination result to “non-detection”(step S741).

Each of the above-described comparison processes may be performed usingthe above-described correlation output strength COL instead of the RSSI.

According to the first embodiment of the present technology, the masterstations and the slave stations can perform the transmission andreception process simultaneously (or substantially simultaneously) andcan reuse radio resources.

For example, when a slave station (for example, the informationprocessing device 100) performs transmission to a master station (forexample, the information processing device 200), a case in which a slavestation (for example, the information processing device 102) of the OBSSside starts transmission before that transmission is assumed.

Even in this case, the control unit 150 of the information processingdevice 100 performs the detection determination according to thephysical header using the detection threshold PD_near or PD_far of thephysical header. For example, as shown in FIG. 12, the carrier sensedetection ranges 31 and 33 of the information processing device 100 areset. Thus, while the information processing device 102 transmits asignal, the control unit 150 of the information processing device 100can treat the signal as not being detected and can perform transmissionto the information processing device 200.

When the information processing device 100 can perform transmission butthe information processing device 200 receives transmission of theinformation processing device 102 earlier, the information processingdevice 200 may not receive the transmission from the informationprocessing device 100. Accordingly, in the first embodiment of thepresent technology, as shown in FIG. 13, the carrier sense detectionranges 41 and 43 of the information processing device 200 are set.Accordingly, the information processing device 200 can wait forreception from the information processing device 100 since thetransmission of the information processing device 102 is not detected.

Here, when the information processing device 200 uniformly raises thedetection thresholds, there is a concern of the packets from theinformation processing device 101 being undetectable. Accordingly, sincetransmission from the information processing device 101 (the legacydevice) located at a long distance is treated with a long-distancephysical header to be detected, the long-distance detection threshold isapplied. Thus, the information processing device 200 can smoothlyreceive reception from each information processing device.

Here, when the IFEE 802.11 standard is assumed, the detection thresholdof the L-STF portion can be set as the “detection threshold” in thefirst embodiment of the present technology. However, instead of thedetection threshold of the L-STF portion, the detection threshold of theL-LTE portion may be set or the detection threshold common to both ofthe L-STF portion and the L-LTF portion may be set. By independentlychanging the detection thresholds of the L-STF portion and the L-LTFportion, both of the detection thresholds may be designated as thephysical header parameters.

The physical header parameters of the self-device may be decided basedon Capability which can be used by the other information processingdevices.

2. Second Embodiment

In the first embodiment of the present technology, the example in whichthe transmission suppression is temporarily cancelled even when thepacket detection determination result is “only-energy detection” and thetransmission suppression is set has been described. That is, the examplein which the transmission suppression is temporarily cancelled despitethe setting of the transmission suppression to transmit the reply packetonly when the packet destined for the self-device is received and thereply immediately after the reception is requested has been described.

In a second embodiment of the present technology, an example in whichnone of the transmission is performed when the packet detectiondetermination result is “only-energy detection” and the transmissionsuppression is set will be described. The configurations of informationprocessing devices in the second embodiment of the present technologyare substantially the same as the configurations of the informationprocessing devices 100 to 103, 200, and 201 shown in FIG. 1 and thelike. Therefore, the same reference numerals as those of the firstembodiment of the present technology are given to common portions tothose of the first embodiment of the present technology, and thedescription thereof will be partially omitted.

Some of the processes and the formats in the second embodiment of thepresent technology are common to those of the first embodiment of thepresent technology. Therefore, the same reference numerals as those ofthe first embodiment of the present technology are given to commonportions to those of the first embodiment of the present technology, andthe description thereof will be partially omitted.

[Operation Example of Transmission and Reception Process]

FIG. 19 is a flowchart showing an example of a processing order of thetransmission and reception process by the information processing device100 according to the second embodiment of the present technology. InFIG. 19, a part of the transmission and reception process shown in FIG.17 is modified. Therefore, the same reference numerals as those of FIG.17 are given to common portions to the transmission and receptionprocess shown in FIG. 17, and the description thereof will be partiallyomitted.

When the determination result obtained in the packet detectiondetermination process is “only-energy detection” (step S723), thecontrol unit 150 of the information processing device 100 basicallytreats a wireless state as a busy state and suppresses transmission fromthe self-device (step S727). When the wireless state is treated as thebusy state in this way, all of the transmission is suppressed in thesecond embodiment of the present technology.

In this way, in the second embodiment of the present technology, all ofthe transmission is suppressed when the determination result obtained inthe packet detection determination process is “only-energy detection.”Thus, it is possible to further improve safety of the operation of thetransmission and reception process.

3. Third Embodiment

In the first embodiment of the present technology, the example in whichLink Strength Category field is set up in the SIGNAL field of the IEEE802.11 standard has been described.

In a third embodiment of the present technology, an example in whichLink Strength Category field is set up in a service field of the WEE802.11 standard will be described. The configurations of informationprocessing devices in the third embodiment of the present technology aresubstantially the same as the configurations of the informationprocessing devices 100 to 103, 200, and 201 shown in FIG. 1 and thelike. Therefore, the same reference numerals as those of the firstembodiment of the present technology are given to common portions tothose of the first embodiment of the present technology, and thedescription thereof will be partially omitted.

Some of the processes and the formats in the third embodiment of thepresent technology are common to those of the first embodiment of thepresent technology. Therefore, the same reference numerals as those ofthe first embodiment of the present technology are given to commonportions to those of the first embodiment of the present technology, andthe description thereof will be partially omitted.

[Example of Format of PPDU]

FIG. 20 is a diagram showing an example of the format of a PPDUexchanged between the devices included in the communication system 10according to the third embodiment of the present technology.

Here, the example shown in FIG. 20 is the same as the example shown inFIG. 7 except that Link Strength Category field is set up in a Servicefield rather than in the SIGNAL field. Accordingly, the same referencenumerals as those of FIG. 7 are given to common portions to those ofFIG. 7, and the description thereof will be partially omitted.

The PPDU is configured to include Preamble 301, SIGNAL 307, Extension303, Service 308, MPDU 305, and FCS 306.

Here, in the third embodiment of the present technology, “Link StrengthCategory field” is newly prepared in a part of the field of Service 308of the physical header. That is, “Link Strength Category field” is newlyset up in a portion treated as being reserved in Service 308 of thephysical header. Then, each information processing device (other than alegacy device) changes “Link Strength Category field” according to thequality of a link with a destination at the time of transmission.

In this way, in the third embodiment of the present technology, “LinkStrength Category field” is set up in the portion treated as beingreserved in Service 308. Thus, as in the first embodiment of the presenttechnology, it is possible to realize the specific function withoutinterfering with reception of the legacy device.

[Operation Example of Transmission and Reception Process]

By replacing “SIGNAL field” with “Service field” in the transmission andreception process (step S735) shown in FIG. 18 and performing the sameprocess as the transmission and reception process shown in FIGS. 17 and18, it is possible to realize the third embodiment of the presenttechnology.

Here, the error detection code including “Link Strength Category field”as the target may be inserted into a reserved field remaining in theservice field. A condition that validity of the content of “LinkStrength Category field” be confirmed by the error detection codeincluding “Link Strength Category field” as the target may be set as anadditional determination condition.

In this way, in the third embodiment of the present technology, LinkStrength Category field is set up in the Service field of the IEEE802.11 standard. Thus, more information can be stored than in the firstembodiment of the present technology. For example, even when the modesof PLCP are set with multiple values, the information can beappropriately stored.

4. Fourth Embodiment

In the first to third embodiments of the present technology, theexamples in which the detection thresholds of PLCP are changed based onthe content of the fields of the physical header have been described.

In a fourth embodiment of the present technology, an example in which aplurality of preamble sequences with different detection thresholds areused on a transmission side and preamble correlation detectors appliedby the RSSI are switched on a reception side will be described. Thus,the reception side can receive only a desired packet. The configurationsof information processing devices in the fourth embodiment of thepresent technology are substantially the same as the configurations ofthe information processing devices 100 to 103, 200, and 201 shown inFIG. 1 and the like. Therefore, the same reference numerals as those ofthe first embodiment of the present technology are given to commonportions to those of the first embodiment of the present technology, andthe description thereof will be partially omitted.

Some of the processes and the formats in the fourth embodiment of thepresent technology are common to those of the first embodiment of thepresent technology. Therefore, the same reference numerals as those ofthe first embodiment of the present technology are given to commonportions to those of the first embodiment of the present technology, andthe description thereof will be partially omitted.

[Example of Format of PPDU]

FIG. 21 is a diagram showing an example of the format of a PPDUexchanged between the devices included in the communication system 10according to the fourth embodiment of the present technology.

Here, the example shown in FIG. 21 is the same as the example shown inFIG. 7 except that Link Strength Category field is not set up in theSIGNAL field, but the plurality of Preamble sequences are defined.Accordingly, the same reference numerals as those of FIG. 7 are given tocommon portions to those of FIG. 7, and the description thereof will bepartially omitted.

The PPDU is configured to include Preamble 311, SIGNAL 312, Extension303, Service 304, MPDU 305, and FCS 306.

Here, in the fourth embodiment of the present technology, a sequence ofa plurality of Preambles 311 is defined. For example, as shown in a ofFIG. 21, a sequence such as “Preamble #1” is defined in Preamble 311. Asshown in b of FIG. 21, a sequence such as “Preamble #0” is defined.Then, each information processing device (other than the legacy device)changes the sequence to be used according to the quality of the linkwith the destination at the time of transmission. FIG. 21 shows anexample in which two kinds of Preambles are prepared, but three or morekinds of Preambles may be prepared.

In the fourth embodiment of the present technology, the physical headerin which the sequence such as “Preamble #0” is used in Preamble 311 isreferred to as a “long-distance physical header.” The physical header inwhich the sequence such as “Preamble #1” is used in Preamble 311 isreferred to as a “short-distance physical header.” The Preamblesequences are generated by different rules and have low mutualcorrelation. Preamble sequence #0 is assumed to be the same sequence asthe Preamble used by the legacy device.

Each information processing device (other than the legacy device)receiving the packet that includes such a physical header changes thecorrelator (and the thresholds determined in detection) to be appliedaccording to the magnitude of the RSSI of a signal.

Here, when the IEEE 802.11 standard is assumed, “another Preamble” isassumed to mean that at least one of L-STF and L-LTF is different.

[Operation Example of Transmission and Reception Process]

FIG. 22 is a flowchart showing a packet detection determination process(the processing order of step S730 shown in FIG. 17) in the transmissionand reception process by the information processing device 100 accordingto the fourth embodiment of the present technology.

First, the control unit 150 of the information processing device 100performs measurement of the RSSI on a signal input via the antenna 141and retains the RSSI obtained through the measurement (step S751).

Subsequently, the control unit 150 of the information processing device100 compares the measured RSSI to the retained application levels (L_farand L_near) of the physical headers and decides the index of thephysical header to be applied to detection (step S752). For example, asin the selection method of selecting the transmission physical header ofthe self-device, it is possible to decide the index of the physicalheader to be applied to the detection.

For example, when the measured RSSI is compared to the value of L_nearand the measured RSSI is greater than L_near, the control unit 150 ofthe information processing device 100 decides 1 (for the short distance)as the index of the physical header to be used for the correlationdetection of the self-device. Conversely, when the measured RSSI isequal to or less than L_near, the control unit 150 of the informationprocessing device 100 decides 0 (for the long distance) as the index ofthe physical header to be used for the correlation detection of theself-device.

In the decision procedure, it is assumed that there is no difference intransmission power between the slave and master stations. However, wheninformation regarding a difference in the transmission power is retainedin advance despite the difference in the transmission power between theslave and master stations, the determination can be performed afterappropriate correction is applied based on the retained informationregarding the difference in the transmission power.

Subsequently, the control unit 150 of the information processing device100 performs correlation calculation using the correlator correspondingto the preamble sequence generated by the different rules, as describedabove, in the physical header with the decided index (step S753). Here,a correlator output is a correlation output strength COL as in the firstembodiment of the present technology. That is, the correlator output isnot a normalized correlator output level, but is a correlator outputconverted by reflecting reception power.

Subsequently, the control unit 150 of the information processing device100 compares the correlator output of the selected correlator to thedetection threshold of the physical header in the decided index todetermine whether the value of the correlator output is greater than thedetection threshold (step S754).

When the value of the correlator output is greater than the detectionthreshold (step S754), the control unit 150 of the informationprocessing device 100 sets the packet detection determination result as“detection” (step S755).

When the value of the correlator output is equal to or less than thedetection threshold (step S754), the control unit 150 of the informationprocessing device 100 compares the measured RSSI to the energy detectionthreshold ED (step S756). Then, the control unit 150 of the informationprocessing device 100 determines whether the RSSI is greater than theenergy detection threshold ED (step S756).

When the RSSI is greater than the energy detection threshold ED (stepS756), the control unit 150 of the information processing device 100sets the packet detection determination result to “only-energydetection” (step S757).

When the RSSI is equal to or less than the energy detection threshold ED(step S756), the control unit 150 of the information processing device100 sets the packet detection determination result to “non-detection”(step S758).

Here, when the IEEE 802.11 standard is assumed, the detection thresholdof the L-STF portion can be set as the “detection threshold” in thefourth embodiment of the present technology. However, instead of thedetection threshold of the L-STF portion, the detection threshold of theL-LTE portion may be set or the detection threshold common to both ofthe L-STF portion and the L-LTF portion may be set. By independentlychanging the detection thresholds of the L-STF portion and the L-LTFportion, both of the detection thresholds may be designated as thephysical header parameters.

5. Fifth Embodiment

A fifth embodiment of the present technology is a modification exampleof the fourth embodiment of the present technology. An example in whicha master station side selects a physical header which is used by asubordinate information processing device will be described. An examplein which a reception side operates correlators of preamble sequenceswhich are candidates normally in parallel will be described.

The configurations of information processing devices in the fifthembodiment of the present technology are substantially the same as theconfigurations of the information processing devices 100 to 103, 200,and 201 shown in FIG. 1 and the like. Therefore, the same referencenumerals as those of the first to fourth embodiments of the presenttechnology are given to common portions to those of the first to fourthembodiments of the present technology, and the description thereof willbe partially omitted.

Some of the processes and the formats in the fifth embodiment of thepresent technology are common to those of the first to fourthembodiments of the present technology. Therefore, the same referencenumerals as those of the first to fourth embodiments of the presenttechnology are given to common portions to those of the first to fourthembodiments of the present technology, and the description thereof willbe partially omitted.

[Example of Beacon Frame Format]

FIG. 23 is a diagram showing an example of a beacon frame formatexchanged between the devices included in a communication system 10according to the fifth embodiment of the present technology. Since FIG.23 is a modification example of FIG. 14, the same reference numerals asthose of FIG. 14 are given to common portions to those of FIG. 14, andthe description thereof will be partially omitted.

FIG. 23 shows an example in which an element such as “Multi DetectAssignment” 321 is newly added to Payload 320 along with “Multi DetectParameter” 311.

In “Multi Detect Assignment” 321, information for specifying thesubordinate information processing devices is stored in “Association ID”323 and 325. In FIG. 23, the example in which Association ID is storedas the information for specifying the information processing devices isshown, but other information capable of specifying the informationprocessing devices may be stored. For example, MAC addresses may bestored.

The index (0 or 1) of the physical header to be used by the informationprocessing devices is stored in “PLCP Header Index” 324 and 326. Suchcombinations are arranged and stored in regard to all of the subordinateinformation processing devices (other than the legacy devices).

The control unit of the information processing device 200 transmits abeacon in which the information indicated in “Multi Detect Parameter”311 and “Multi Detect Assignment” 321 is stored to nearby informationprocessing devices to inform the nearby information processing devicesof the beacon.

[Communication Example of Physical Header Parameter Sharing Process]

FIG. 24 is a sequence chart showing an example of a connection processbetween the devices included in the communication system 10 according tothe fifth embodiment of the present technology.

Since FIG. 24 is a modification example of FIG. 15, the description ofcommon portions to those of FIG. 15 will be partially omitted. That is,FIG. 24 shows an example in which physical header parameters areincluded in a beacon to be transmitted and information for designatingthe physical header to be used by each subordinate informationprocessing device is also included in the beacon to be transmitted.

First, the control unit of the information processing device 200 storesa set of the detection threshold of each physical header, and theapplication level of each physical header and the index of each physicalheader in “Multi Detect Parameter” 311 (shown in FIG. 23) of the beacon(431).

The control unit of the information processing device 200 stores the setof the information for designating the physical header to be used byeach subordinate information processing device in “Multi DetectAssignment” 321 (shown in FIG. 23) of the beacon (432).

Here, a case in which content of the “Multi Detect Assignment” field isstored will be described. The control unit of the information processingdevice 200 confirms whether a generation function and a correlationdetection function for the Preamble sequences designated by theCapability of each subordinate information processing device aresupported, and then stores only the corresponding Preamble sequence.When each subordinate information processing device corresponding to aspecific function selects the physical header to be used, informationregarding link quality between the master station and each subordinateslave station is determined to be used. Therefore, packets received fromdestinations connected to the self-device are monitored (or retainedmeasured values are read) and the RSSI for each destination is acquiredto be used. Instead of the RSSI, the above-described correlation outputstrength COL may be used.

Subsequently, the control unit of the information processing device 200transmits the beacon to the subordinate information processing devices(433 and 434).

When the beacon from the information processing device 200 is received(434), the control unit 150 of the information processing device 100acquires and retains each piece of content included in the beacon (435).That is, the control unit 150 of the information processing device 100acquires and retains the content of “Multi Detect Parameter” 311 and thecontent of “Multi Detect Assignment” 321 (shown in FIG. 23) included inthe beacon (435).

The control unit 150 of the information processing device 100 uses thecorresponding physical header according to the index of the physicalheader designated with the beacon by the master station (the informationprocessing device 200). That is, the control unit 150 of the informationprocessing device 100 does not perform the autonomous determination.

[Operation Example of Transmission and Reception Process]

FIG. 25 is a flowchart showing a packet detection determination process(the processing order of step S730 shown in FIG. 17) in the transmissionand reception process by the information processing device 100 accordingto the fifth embodiment of the present technology.

FIG. 25 shows an example in which each master station and each slavestation corresponding to the specific function operate all of thecorrelators of the PLCP Preambles supported by the self-device inparallel.

First, the control unit 150 of the information processing device 100performs measurement of the RSSI on a signal input via the antenna 141and retains the RSSI obtained through the measurement (step S761).

Subsequently, the control unit 150 of the information processing device100 inputs an input signal to each correlator and performs correlationcalculation (step S762). That is, the control unit 150 of theinformation processing device 100 calculates correlation between thepreambles simultaneously in the correlators (step S762).

Here, as each detection threshold for determining the detection based oneach correlator output, the detection threshold of each physical headerdesignated from the master station is used in the physical headerparameter sharing process. The correlator output is the correlationoutput strength COL as in the first embodiment of the presenttechnology. That is, the correlator output is not a normalizedcorrelator output level, but is a correlator output converted byreflecting reception power.

Subsequently, the control unit 150 of the information processing device100 determines whether the correlator output of a certain correlatoramong the plurality of correlators is greater than the correspondingdetection threshold (step S763).

When the correlator output of the certain correlator among the pluralityof correlators is greater than the corresponding detection threshold(step S763), the control unit 150 of the information processing device100 sets the packet detection determination result as “detection” (stepS764).

When none of the correlator outputs of the plurality of correlators isgreater than the corresponding detection threshold (step S763), thecontrol unit 150 of the information processing device 100 compares themeasured RSSI to the energy detection threshold ED (step S765). Then,the control unit 150 of the information processing device 100 determineswhether the RSSI is greater than the energy detection threshold ED (stepS765).

When the RSSI is greater than the energy detection threshold ED (stepS765), the control unit 150 of the information processing device 100sets the packet detection determination result to “only-energydetection” (step S766).

When the RSSI is equal to or less than the energy detection threshold ED(step S765), the control unit 150 of the information processing device100 sets the packet detection determination result to “non-detection”(step S767).

6. Sixth Embodiment

A sixth embodiment of the present technology is a modification exampleof the fourth embodiment of the present technology. An example in whicha plurality of PLCP preambles for discrimination are generated byprocessing part of an original sequence rather than completely differentsequences will be described. Thus, it is possible to simplify theconfiguration of the plurality of correlators on a reception side. Bysetting the preamble sequence of the processing origin as a sequence ofa format for a legacy device, it is also possible to detect a preamblefor an information processing device not corresponding to a specificfunction according to a condition, and thus it is possible to allowbackward compatibility to partially remain.

The configurations of information processing devices in the sixthembodiment of the present technology are substantially the same as theconfigurations of the information processing devices 100 to 103, 200,and 201 shown in FIG. 1 and the like. Therefore, the same referencenumerals as those of the first to fourth embodiments of the presenttechnology are given to common portions to those of the first to fourthembodiments of the present technology, and the description thereof willbe partially omitted.

Some of the processes and the formats in the sixth embodiment of thepresent technology are common to those of the first to fourthembodiments of the present technology. Therefore, the same referencenumerals as those of the first to fourth embodiments of the presenttechnology are given to common portions to those of the first to fourthembodiments of the present technology, and the description thereof willbe partially omitted.

[Example of Format of PPDU]

The format of the PPDU in the sixth embodiment of the present technologyis the same as the example of the format shown in FIG. 21.

That is, in the sixth embodiment of the present technology, a sequenceof a plurality of Preambles 311 (in FIG. 21) is defined. For example, asshown in a of FIG. 21, a sequence such as “Preamble #1” is defined inPreamble 311. As shown in b of FIG. 21, a sequence such as “Preamble #0”is defined. Then, each information processing device (other than thelegacy device) changes the sequence to be used according to the qualityof the link with the destination at the time of transmission. FIG. 21shows an example in which two kinds of Preambles are prepared, but threeor more kinds of Preambles may be prepared.

In the sixth embodiment of the present technology, the physical headerin which the sequence such as “Preamble #0” is used in Preamble 311 isreferred to as a “long-distance physical header.” The physical header inwhich the sequence such as “Preamble #1” is used in Preamble 311 isreferred to as a “short-distance physical header.” Preamble sequence #0is assumed to be the same sequence as the Preamble used by the legacydevice.

Here, the sixth embodiment of the present technology and the fourthembodiment of the present technology are different in a method ofgenerating a Preamble sequence other than Preamble #0. Specifically, inthe sixth embodiment of the present technology, a sequence other thanPreamble #0 is obtained by processing a part of the content throughpositive and negative inversion using Preamble #0 as a base. Theprocessing is not limited to the positive and negative inversion. Forexample, another calculation may be performed, for example, a part ofcontent may be decimated and set to 0, as long as a certain sequence isused as a base to perform the processing.

Here, when the IEEE 802.11 standard is assumed, “another Preamblesequence” is assumed to mean a sequence in which a difference is made byapplying the above-described processing to at least one of L-STF andL-LTF.

Each information processing device (other than the legacy device)receiving the packet that includes such a physical header changes thecorrelation calculation (and the packet detection determinationthreshold) to be applied according to the magnitude of the RSSI of asignal.

[Operation Example of Physical Header Parameter Decision Process]

A physical header parameter decision process in the sixth embodiment ofthe present technology is substantially the same as that of the fourthembodiment of the present technology. Here, in the sixth embodiment ofthe present technology, the following extension may be added to arelation expression of a determination standard of the detectionthreshold of each physical header.

The above-described Expressions 3 and 6 may be replaced by introducing athreshold offset in which deterioration due to the inclusion of theprocessing such as the positive and negative inversion is consideredinto the preamble sequence. For example, when an output expectationvalue of the original correlator with respect to an input of thepreamble of which a part is subjected to the positive and negativeinversion is multiplied by A, Expression 3 can be changed to thefollowing Expression 11 and Expression 6 can be changed as in thefollowing Expression 12. Here, Expressions 11 and 12 are description inwhich calculation in logarithm (dB) is assumed.

PD_near>COL_other_near+A_near  Expression 11

PD_n>COL_other_n+A_n  Expression 12

(where n=0 to N)

[Operation Example of Transmission and Reception Process]

FIG. 26 is a flowchart showing a packet detection determination process(the processing order of step S730 shown in FIG. 17) in the transmissionand reception process by the information processing device 100 accordingto the sixth embodiment of the present technology.

First, the control unit 150 of the information processing device 100performs measurement of the RSSI on a signal input via the antenna 141and retains the RSSI obtained through the measurement (step S771).

Subsequently, the control unit 150 of the information processing device100 compares the measured RSSI to the retained application levels (L_farand L_near) of the physical headers and decides the index of thephysical header to be applied to detection (step S772). For example, asin the selection method of selecting the transmission physical header ofthe self-device, it is possible to decide the index of the physicalheader to be applied to the detection.

For example, when the measured RSSI is compared to the value of L_nearand the measured RSSI is greater than L_near, the control unit 150 ofthe information processing device 100 decides 1 (for the short distance)as the index of the physical header to be used for the correlationdetection of the self-device. Conversely, when the measured RSSI isequal to or less than L_near, the control unit 150 of the informationprocessing device 100 decides 0 (for the long distance) as the index ofthe physical header to be used for the correlation detection of theself-device.

In the decision procedure, it is assumed that there is no difference intransmission power between the slave and master stations. However, wheninformation regarding a difference in the transmission power is retainedin advance despite the difference in the transmission power between theslave and master stations, the determination can be performed afterappropriate correction is applied based on the retained informationregarding the difference in the transmission power.

Subsequently, the control unit 150 of the information processing device100 switches internal calculation of the correlator and performs thecorrelation calculation to correspond to the preamble sequence of thephysical header with the decided index (step S773). Here, the switchingof the internal calculation is the same process as the processcorresponding to “positive and negative inversion on a part of content”which is the above-described method of generating the PLCP Preambleportion.

[Example of Configuration of Correlator]

FIG. 27 is a diagram showing an example of the configuration of acorrelator included in the information processing device 100 accordingto the sixth embodiment of the present technology. Here, a of FIG. 27 isa modification example of a of FIG. 11 and b of FIG. 27 is amodification of b of FIG. 11. FIG. 27 shows an example of theconfiguration of the correlator in which calculation of sign inversionis applied based on a switch signal determined with the RSSI. Byrealizing the configuration in this way, it is possible to easilyconfigure the correlator of another preamble.

For example, when an input PLCP Preamble is correctly consistent withcalculation of the correlator, it is possible to obtain a largecorrelator output. However, when the calculation is different, thecorrelator output decreases. Therefore, the packet to be detected canaccordingly be selected. Here, definition of the “correlator output” isthe same as the above-described definition of the “correlator output.”

For example, the calculation of the correlator may be switched tocorrespond to the preamble sequence of the physical header with thedecided index or the detection threshold may be switched withoutchanging the calculation. Both of the calculation and the detectionthreshold may be switched. Thus, it is possible to realize the processof selecting the packet to be detected according to a situation. FIG. 26shows an example in which both of the calculation and the detectionthreshold are switched.

In FIG. 26, the control unit 150 of the information processing device100 switches the calculation of the correlator and the detectionthreshold to correspond to the preamble sequence of the physical headerwith the decided index (step S773). That is, the calculation of thecorrelator and the detection threshold are set based on the decidedindex (step S773).

Subsequently, the control unit 150 of the information processing device100 compares the correlator output to the corresponding detectionthreshold to determine whether the value of the correlator output isgreater than the detection threshold (step S774).

When the value of the correlator output is greater than the detectionthreshold (step S774), the control unit 150 of the informationprocessing device 100 sets the packet detection determination result as“detection” (step S775).

When the value of the correlator output is equal to or less than thedetection threshold (step S774), the control unit 150 of the informationprocessing device 100 compares the measured RSSI to the energy detectionthreshold ED (step S776). Then, the control unit 150 of the informationprocessing device 100 determines whether the RSSI is greater than theenergy detection threshold ED (step S776).

When the RSSI is greater than the energy detection threshold ED (stepS776), the control unit 150 of the information processing device 100sets the packet detection determination result to “only-energydetection” (step S777).

When the RSSI is equal to or less than the energy detection threshold ED(step S776), the control unit 150 of the information processing device100 sets the packet detection determination result to “non-detection”(step S778).

7. Seventh Embodiment

In the first to sixth embodiments of the present technology, thecommunication examples between the master and slave stations in the startype topology configured by the master and subordinate slave stationshave been described. In the communication examples, the destination ofthe subordinate slave stations is restricted to the master station.Here, the first to sixth embodiments of the present technology can alsobe applied to direct communication between subordinate slave stations.

Accordingly, in a seventh embodiment of the present technology, anexample in which direct communication between subordinate slave stations(for example, communication between information processing devices 101and 104 shown in FIG. 28) is performed will be described.

[Configuration Example of Communication System]

FIG. 28 is a diagram showing a system configuration example of acommunication system 50 according to the seventh embodiment of thepresent technology.

FIG. 28 is a modification example of FIG. 1 and is different from FIG. 1in that the information processing device 104 is added. Theconfiguration of the information processing device 104 is substantiallythe same as the configurations of the information processing devices 100to 103, 200, and 201 shown in FIG. 1 and the like. Therefore, the samereference numerals as those of the first to sixth embodiments of thepresent technology are given to common portions to those of the first tosixth embodiments of the present technology, and the description thereofwill be partially omitted.

The communication system 50 is configured to include informationprocessing devices 100 to 104, 200, and 201.

The information processing device 104 is an information processingdevice corresponding to the information processing devices 100 to 103and is, for example, a portable information processing device that has awireless communication function.

In this way, in the seventh embodiment of the present technology, anexample in which direct communication between subordinate slave stations(for example, communication between the information processing devices101 and 104) in the star type topology configured by the master andsubordinate slave stations is performed will be described.

[Communication Example]

FIG. 29 is a sequence chart showing a communication processing examplebetween the devices included in the communication system 50 according tothe seventh embodiment of the present technology.

FIG. 29 shows an example of a communication process when directtransmission between the information processing devices 100 and 104 isperformed. The same also applies to a relation between the other slavestations.

Here, a setup process of the direct communication basically conforms toa tunneling direct link setup (TDLS) function of the IEEE 802.11standard. In FIG. 29, a state in which the information processingdevices 100 and 104 are already connected to the information processingdevice 200 and the operation described in the first embodiment of thepresent technology is performed is assumed in the description.

First, a direct link connection process is performed among theinformation processing devices 100, 104, and 200 (441). That is, each ofthe information processing devices 100 and 104 performs an establishmentprotocol of the direct link via the access point (the informationprocessing device 200) (441). Thus, a direct link searching process canbe performed without alteration of the protocol. The direct linkconnection process is the same as the standard definition, and thus thedetailed description will be omitted herein.

Subsequently, the control unit of the information processing device 200performs a physical header parameter decision process (442). In thisway, in the seventh embodiment of the present technology, the masterstation (the information processing device 200) decides the physicalheader parameters used in the direct link between subordinate slavestations. Therefore, the slave stations do not perform the physicalheader parameter decision process. The physical header parameterdecision process by the master station is the same as that of the firstembodiment of the present technology.

Subsequently, a physical header parameter sharing process is performedamong the information processing devices 100, 104, and 200 (443). Inthis way, in the seventh embodiment of the present technology, thephysical header parameters to be used in the direct link between thesubordinate slave stations are also decided by the master station (theinformation processing device 200). Therefore, the physical headerparameter sharing process is not performed between the slave stationsperforming the direct link. The physical header parameter sharingprocess between the master and slave stations is the same as that of thefirst embodiment of the present technology.

Subsequently, each of the information processing devices 100 and 104performs the use physical header decision process (444 and 446). Here,the physical header for the partner during the direction link connectionis decided according the communication quality of the link with thepartner independently from the master station. The standard or the likeof the determination is the same as that of the first embodiment of thepresent technology. That is, the use physical header decision processbetween the slave stations is the same as that of the first embodimentof the present technology.

Subsequently, each of the information processing devices 100 and 104performs the transmission and reception process (445 and 447). Thetransmission and reception process is the same as that of the firstembodiment of the present technology except that the transmission andreception between the slave stations are performed instead of thetransmission and reception between the master and slave stations. Theformat of the PPDU in the seventh embodiment of the present technologyis the same as that of the first embodiment of the present technology.

8. Eighth Embodiment

In the seventh embodiment of the present technology, the example inwhich the master station decides the physical header parameters used forthe direct link has been described. However, the slave stations (theslave stations performing direct link) may decide the physical headerparameters used for the direct link.

Accordingly, in an eighth embodiment of the present technology, anexample in which slave stations (slave stations performing the directlink) decide physical header parameters used for the direct link will bedescribed.

The system configuration according to the eighth embodiment of thepresent technology is the same as that of the seventh embodiment of thepresent technology. Therefore, the same reference numerals as those ofthe seventh embodiment of the present technology are given to commonportions to those of the seventh embodiment of the present technology,and the description thereof will be partially omitted.

[Communication Example]

FIG. 30 is a sequence chart showing a communication processing examplebetween devices included in a communication system 50 according to theeighth embodiment of the present technology.

FIG. 30 is a modification example of FIG. 29 and there are commonportions to those of FIG. 29. Therefore, the description of the commonportions to those of FIG. 29 will be partially omitted.

First, a direct link connection process is performed among theinformation processing devices 100, 104, and 200 (451). The direct linkconnection process is the same as that of the seventh embodiment of thepresent technology.

Subsequently, each of the information processing devices 100 and 104performs a physical header parameter decision process (452 and 453). Inthis way, in the eighth embodiment of the present technology, the slavestations (the information processing devices 100 and 104) with whichthere are connection destinations other than the master stationautonomously decide the physical header parameters for the direct link.The physical header parameter decision process can be performed insubstantially the same way as the process performed by the masterstation (the information processing device 200) in the first embodimentof the present technology. However, sampling targets of COL_self_nearand COL_self_far are the same BSSID, but are different in that thesampling targets are restricted to the slave stations (the informationprocessing devices) directly connected to the self-device.

Subsequently, a physical header parameter sharing process is performedbetween the information processing devices 100 and 104 (454). In thisway, each of the information processing devices 100 and 104 performingthe direct link periodically exchanges the physical header parametersfor the direct link decided through the physical header parameterdecision process in the direct link. Then, each of the informationprocessing devices 100 and 104 ascertains an operation expected by thedirect link partner. A frame to be used for the exchange may be set to adata frame or may be set to a management frame.

Subsequently, each of the information processing devices 100 and 104performs a use physical header decision process (455 and 457). In thisway, each of the information processing devices 100 and 104independently decides the physical header for each partner based on theparameters notified of by the direct link partner apart from theparameters for the master station. The standard or the like of thedetermination is the same as that of the first embodiment of the presenttechnology.

Subsequently, each of the information processing devices 100 and 104performs the transmission and reception process (456 and 458). Thetransmission and reception process is the same as that of the seventhembodiment of the present technology

9. Ninth Embodiment

In the first embodiment of the present technology, the example in whichLink Strength Category field is set up in the SIGNAL field of the IEEE802.11 standard has been described.

In a ninth embodiment of the present technology, an example in which afield storing information regarding a BSS identifier is added to theSIGNAL field of the IEEE 802.11 standard in addition to Link StrengthCategory field will be described. By storing the information regardingthe BSS identifier in this way, it is possible to further improve packetselection precision. The configurations of information processingdevices in the ninth embodiment of the present technology aresubstantially the same as the configurations of the informationprocessing devices 100 to 103, 200, and 201 shown in FIG. 1 and thelike. Therefore, the same reference numerals as those of the firstembodiment of the present technology are given to common portions tothose of the first embodiment of the present technology, and thedescription thereof will be partially omitted.

Some of the processes and the formats in the ninth embodiment of thepresent technology are common to those of the first embodiment of thepresent technology. Therefore, the same reference numerals as those ofthe first embodiment of the present technology are given to commonportions to those of the first embodiment of the present technology, andthe description thereof will be partially omitted.

[Example of format of PPDU]

FIG. 31 is a diagram showing an example of the format of a PPDUexchanged between the devices included in the communication system 10according to the ninth embodiment of the present technology.

Here, the example shown in FIG. 31 is the same as the example shown inFIG. 7 except that a BSS COLOR field is set up in the SIGNAL field.Accordingly, the same reference numerals as those of FIG. 7 are given tocommon portions to those of FIG. 7, and the description thereof will bepartially omitted.

The PPDU is configured to include Preamble 301, SIGNAL 331, Extension303, Service 304, MPDU 305, and FCS 306.

In the ninth embodiment of the present technology, the “Link StrengthCategory” field and the “BSS COLOR” field storing information (COLORinformation) regarding the BSS identifier are set up in parts of theSIGNAL field of the physical header. In FIG. 31, the “Link StrengthCategory” field is indicated by Link Strength Category and the “BSSCOLOR” field is indicated by COLOR.

Here, the COLOR information (BSS COLOR information) is information whichis informed of in advance by a connected partner device (for example,the master station) and is information (for example, a numerical value)which can identify a basic service set (BSS) to which the self-devicebelongs. That is, the COLOR information (BSS COLOR information) is anexample of an identifier for identifying a network. The BSSID is storedas the same information in the MAC header. Here, the COLOR informationcan be expressed in a physical layer (PLCP layer) in a simpler form thanthe BSSID.

An example of a case in which the information processing device (themaster or slave station) transmitting the physical header belongs to theBSS set to “1” as the COLOR information is shown in a and b of FIG. 31.

In this way, in the ninth embodiment of the present technology, the“Link Strength Category” field and the “COLOR” field are set up inportions treated as being reserved in the SIGNAL 311. Thus, it ispossible to realize the specific function in the ninth embodiment of thepresent technology without interfering with reception of the legacydevice.

In the ninth embodiment of the present technology, a physical header ofLink Strength Category=0 is referred to as a “long-distance physicalheader.” Further, a physical header of Link Strength Category=1 isreferred to as a “short-distance physical header.” A physical headertransmitted from a legacy device is assumed to be treated as a“long-distance physical header.”

The information processing device (other than the legacy device)receiving a packet that includes at least one of the Link StrengthCategory field and the COLOR field can acquire content of each of thefields. Then, based on the content of each of the fields, theinformation processing device can change the reception operation and thedetection threshold to be applied.

A connection process is the same as that of the first embodiment of thepresent technology. A physical header parameter decision process is alsosubstantially the same as that of the first embodiment of the presenttechnology. Here, the COLOR information is information which can beacquired in the physical layer. Therefore, unlike the BSSID information,the COLOR information can be used without waiting for a combination ofFCS (present at the end of the PPDU) in the PPDU. Accordingly, when thephysical header parameter decision process is performed, classificationcan be performed using the COLOR information rather than the BSSID whenthe master station collects information regarding communication qualityof packets from other BSSs (OBSSs).

The order of a physical header parameter sharing process is the same asthat of the first embodiment of the present technology. In the ninthembodiment of the present technology, however, information regarding“COLOR” (the BSS identifier in the physical layer) and “TxPower”(transmission power of the master station) is also additionallytransferred in addition to “Multi Detect Parameter.” An example of theframe format used in this case is shown in FIG. 32.

[Example of Beacon Frame Format]

FIG. 32 is a diagram showing an example of a beacon frame formatexchanged between the devices included in a communication system 10according to the ninth embodiment of the present technology. Since FIG.32 is a modification example of FIG. 14, the same reference numerals asthose of FIG. 14 are given to common portions to those of FIG. 14, andthe description thereof will be partially omitted.

FIG. 32 shows an example in which elements such as “COLOR Info” 341 and“TxPower Info” 342 are newly added to Payload 340 in addition to “MultiDetect Parameter” 311.

The BSS identifier in the physical layer is stored in “COLOR Info” 341.The BSS identifier corresponds to the BSS identifier stored in the “BSSCOLOR” field shown in FIG. 31.

Information regarding transmission power of the information processingdevice (for example, the master station) transmitting a beacon is storedin “TxPower Info” 342.

For example, the control unit of the information processing device 200transmits a beacon in which the information is stored in “Multi DetectParameter” 311, “COLOR Info” 341, and “TxPower Info” 342 to the nearbyinformation processing devices to inform the nearby informationprocessing devices of the beacon.

The information processing device informed of the beacon acquires theinformation stored in “Multi Detect Parameter” 311, “COLOR Info” 341,and “TxPower Info” 342 from the beacon to retain the information. Thatis, the information processing device retains content of “Multi DetectParameter,” the BSS identifier in the physical layer, and thetransmission power of a communication partner (for example, the masterstation).

When the content of the beacon is retained and subsequently informationincluded in a subsequent beacon is changed, information included in alatest beacon (latest information) is adopted and retained.

The master station may notify of the content of “Multi DetectParameter,” the BSS identifier in the physical layer, and thetransmission power of the self-device using a signal other than thebeacon transmission. For example, the master station may perform thenotification using a unicast data frame or management frame to asubordinate terminal using determination by the self-device or aninformation acquisition request from the subordinate terminal as atrigger.

[Example of Backoff Process]

FIG. 33 is a diagram showing the flow of a backoff process in the IEEE802.11 standard. In FIG. 33, the horizontal axis represents a time axis.On the upper side of the horizontal axis, states of the informationprocessing device (BUSY 500 to BUSY 502, IFS, and Tx 503) areschematically indicated by rectangles. On the lower side of thehorizontal axis, numerical values indicating the number of backoff slots(backoff counters) are shown. A timing of a request 504 for transmissionfrom an upper layer and a timing of random backoff time generation 505are schematically indicated by rectangles and arrows.

For example, when a carrier sense state transitions to an IDLE stateafter BUSY, a latency time of the IFS is inserted every time. Forexample, when the carrier sense state transitions to the IDLE stateafter BUSY 500 to BUSY 502, the latency time of the IFS is inserted. Thebackoff counter remains stopped during reception of the physical header,as indicated by numerical values on the lower side of the horizontalaxis shown in FIG. 33.

[Example of Backoff Process when Reception is Cancelled]

FIG. 34 is a diagram showing the flow of a backoff process by theinformation processing device 100 according to the ninth embodiment ofthe present technology. The horizontal axis, states (BUSY 510 to BUSY512 and IFS) of the information processing device on the upper side ofthe horizontal axis, and numerical values indicating the number ofbackoff slots (backoff counter) on the lower side of the horizontal axisshown in FIG. 34 are the same as those in FIG. 33.

FIG. 34 shows an example of a case in which two information processingdevices 521 and 522 located at positions distant from the informationprocessing device 100 transmit packets. The horizontal axis related tothe information processing devices 521 and 522 and states (PLCP 513,PLCP 514, and PSDU) of the information processing devices on the upperside of the horizontal axis are the same as those in FIG. 33.

FIG. 34 shows an example in which the information processing device 100stops receiving packets based on PLCP 513 and PLCP 514 included in thepackets when the information processing device 100 receives the packetstransmitted from the information processing devices 521 and 522 (515 and516). Thus, it is possible to shorten times of BUSY 511 and BUSY 512.

However, for example, in an environment that is crowded with theinformation processing devices and in which traffic is congested, thebackoff counter is assumed not to decrease even when a process ofstopping the reception from the distant information processing devicesand transitioning to the IDLE state is performed. For example, as shownin FIG. 34, even when the reception of the packets from the informationprocessing devices 521 and 522 is stopped (515 and 516), the backoffcounter remains “8” and does not decrease from “8” in this state. Inthis way, even when the frame reception determined to be ignorable iscancelled, IFS is added after transition from BUSY to IDLE. Therefore,during the IFS, the backoff counter does not decrease in this state.Until the backoff counter becomes 0, the information processing device100 may not perform transmission. In this way, in the crowdedenvironment (congested environment), there is a concern of atransmission opportunity not increasing even when the reception ofignorable packets is stopped. Accordingly, it is important to improve anadvantageous effect of obtaining a transmission opportunity of theinformation processing device 100. An example in which the transmissionopportunity of the information processing device 100 is improved isshown in FIG. 35.

[Example of Backoff Process when Backoff Counter Decreases withoutInserting IFS]

FIG. 35 is a diagram showing the flow of a backoff process by theinformation processing device 100 according to the ninth embodiment ofthe present technology. Since FIG. 35 is an example corresponding toFIG. 34, the same reference numerals are given to common portions tothose of FIG. 34, and the description thereof will be partially omitted.

As in FIG. 34, FIG. 35 shows an example in which, when the informationprocessing device 100 receives packets transmitted from the informationprocessing devices 521 and 522, the reception is stopped based on thePLCP 513 and PLCP 514 included in the packets (515 and 516). In FIG. 35,the reception is stopped (the reception is cancelled) and the backoffcounter decreases by a time (elapsed time) related to the reception,assuming the IDLE state. In FIG. 35, immediately after the reception isstopped (the reception is cancelled), the backoff counter decreaseswithout latency of IFS (that is, without inserting IFS).

For example, as shown in FIG. 35, when reception of a packet from theinformation processing device 521 is stopped (515), a time length from astart time of the physical header to a current time is calculated. Then,a time slot conversion value of the length (time length) is subtractedfrom the backoff counter at a time. For example, “4 (=8−4)” iscalculated as the time length from the start time of the physical headerto the current time. Then, the value “4” is subtracted from the backoffcounter “8” and “4” is obtained as the backoff counter. Further,application of IFS before subsequent carrier sense is also cancelled andsubtraction of the backoff counter instantly starts.

In this way, by cancelling the application of IFS and subtracting thebackoff counter corresponding to a physical header time, it is possibleto efficiently obtain a transmission opportunity.

Here, for example, when enhanced distributed channel access (EDCA) isused, a plurality of backoff counters operate in some cases.Accordingly, when the plurality of backoff counters operate, thisprocess is performed on all of the counters.

In this way, the control unit 150 of the information processing device100 can perform control such that a latency time corresponding to IFSdoes not occur after the stop of the reception. In this case, after thestop of the reception of the packet, the control unit 150 can convert atime length from a transition time of the carrier sense to BUSY to areception stop time at the time of reception of the packet into a slottime and can subtract the slot time from the backoff counter.

Here, in the above-described subtraction process, the backoff counterafter the subtraction is also assumed to be a negative value. In thiscase, the counter can be set to 0. That is, when a result after thesubtraction is a negative value, the control unit 150 of the informationprocessing device 100 can treat the result as 0.

As another variation, when the backoff counter after the subtraction isa negative value, the result may be returned to the positive absolutevalue of the negative value and then used. For example, when a time slotconversion value of the time length in which a counter value beforesubtraction is 1 and is BUSY is 2, a value “−1 (=1−2)” after thesubtraction is returned and the counter value can remain 1. Thus, whenthere are different information processing devices under the samecondition that the counter value before the subtraction be 2, cases inwhich counts simultaneously become 0 and collision occurs can bereduced. However, in the return case, the return in the result isgreater than the counter value before the subtraction is prohibited.That is, when a result after the subtraction is a negative value, thecontrol unit 150 of the information processing device 100 can set avalue obtained by returning the negative value to a positive value sothat the value does not exceed the backoff counter before thesubtraction.

As still another variation, when the backoff counter after thesubtraction is a negative value, a random number may be generated in therange between a value equal to or less than the backoff counter beforethe subtraction and 0 and the random number may be set to a value afterthe subtraction. That is, the random backoff may be performed with awidth of the original value of the backoff counter before Busy.

In this example, the carrier sense of the physical layer has beendescribed. However, when transmission suppression is applied by virtualcarrier sense and a BUSY state is entered, the above-described processat the time of stop of the reception may not be performed.

[Operation Example of Use Physical Header Decision Process]

FIG. 36 is a flowchart showing an example of a processing order of a usephysical header decision process (transmission physical header selectionprocess) by the information processing device 100 according to the ninthembodiment of the present technology. The use physical header decisionprocess is basically the same as that of the first embodiment of thepresent technology, but is different in that RSSI_peer is correctedbased on TxPower notified of by a partner.

First, the control unit 150 of the information processing device 100monitors packets received from designations connected to the self-deviceand acquires the RSSI of each designation (step S781). The RSSI(monitoring result) acquired in this way is set to RSSI_peer.

When measured values of the packets received from the destinationsconnected to the self-device are retained, the control unit 150 of theinformation processing device 100 may read the measured value to acquirethe RSSI of each destination (step S781).

Here, in the case of the information processing device (for example, theinformation processing device 100) connected to the master station (forexample, the information processing device 200), only the master stationis basically set as the destination. In this case, the reception levelof a previous beacon may be used as a monitoring result.

Subsequently, the control unit 150 of the information processing device100 corrects the acquired RSSI_peer in consideration of a transmissionpower difference (step S782). For example, “TxPower” information (storedin “TxPower Info” 342 shown in FIG. 32) notified of by the masterstation in the physical header parameter sharing process is referred toas TP_peer. Further, transmission power to be used for transmission tothe master station by the information processing device 100 is referredto as TP_self. In this case, the corrected RSSI_adjusted can be obtainedby the following Expression 13. Here, Expression 13 is description inwhich calculation in logarithm (dB) is assumed.

RSSI_adjusted=RSSI_peer+(TP_self−TP_peer)  Expression 13

Here, RSSI_adjusted indicates an estimated value of the RSSI expectedwhen the master station side receives transmission from the informationprocessing device 100. However, when information corresponding toTP_peer may not be obtained, RSSI_adjusted may be substituted withRSSI_peer.

Subsequently, the control unit 150 of the information processing device100 compares the corrected RSSI_adjusted to the application level L_nearof the physical header and decides the index of the physical header tobe used for transmission by the self-device based on the comparisonresult (step S783). The application level L_near of the physical headeris included in a beacon transmitted from the information processingdevice 200.

For example, when the corrected RSSI_adjusted is greater than theapplication level L_near of the physical header, the control unit 150 ofthe information processing device 100 decides 1 (for the short distance)as the index of the physical header to be used for transmission by theself-device (step S783). Conversely, when the corrected RSSI_adjusted isequal to or less than the application level L_near of the physicalheader, the control unit 150 of the information processing device 100decides 0 (for the long distance) as the index of the physical header tobe used for transmission by the self-device (step S783).

When the index of the physical header to be used for transmission by theself-device is already decided and a new index is decided, the alreadydecided index is updated to the new index (step S783).

In FIG. 36, the example in which the use physical header is decidedbased on the classification of two values of the short distance and thelong distance has been described, but the use physical header may bedecided based on classification of three or more values (N values). Forexample, the application levels of the physical headers are set to L_0,L_1, . . . , L_N in order for the long distance. In this case, nsatisfying the following relation expression (Expression 14) is selectedas the index of the physical header to be used for transmission. Here,Expression 14 is description in which calculation in logarithm (dB) isassumed.

L_n≦RSSI_adjusted<L_n+1  Expression 14

(where n=0 to N)

In FIG. 36, the operation example on the slave station side in the caseof uplink transmission from the slave station side to the master stationside has been described. However, in the case of downlink transmission,the same operation may be performed on the master station side. In thiscase, the content of the process on the master station side is the sameas the content of the process shown in FIG. 36. However, when there area plurality of connection partners, classification of monitoring resultsof received packets is assumed to be managed for each of the packettransmission sources and RSSI_adjusted is assumed to be calculatedindividually for each link.

The example in which the RSSI is used has been described in FIG. 36.However, the correlation output strength COL may be used instead of theRSSI.

[Operation Example of Transmission and Reception Process]

FIG. 37 is a flowchart showing an example of a processing order of atransmission and reception process by the information processing device100 according to the ninth embodiment of the present technology. In FIG.37, the information processing device 100 will be described, but thesame can also apply to the other information processing devices (forexample, the information processing device 200). That is, thetransmission and reception process is the same on both of the masterstation side and the terminal side.

The control unit 150 of the information processing device 100 performs apacket detection and reception determination process for a time otherthan during transmission and reception (step S800). The packet detectionand reception determination process will be described in detail withreference to FIG. 39.

Subsequently, the control unit 150 of the information processing device100 determines whether there is a packet to be transmitted (step S791).When there is no packet to be transmitted (step S791), the operation ofthe transmission and reception process ends.

When there is a packet to be transmitted (step S791), the control unit150 of the information processing device 100 determines whether theinformation processing device 100 acquires a transmission right (stepS792).

Here, the acquisition state of the transmission right is assumed to be,for example, a state in which a backoff counter in which the carriersense result decreases according to an IDLE time is 0.

When the information processing device 100 acquires the transmissionright (step S792), the control unit 150 of the information processingdevice 100 transmits the packet (step S794). When the informationprocessing device 100 does not acquire the transmission right (stepS792), the control unit 150 of the information processing device 100determines whether the packet to be transmitted is an instant reply to apacket received from a communication partner (step S793).

A packet which is an instant reply to the packet received from thecommunication partner is, for example, a CTS frame, an ACK frame, aBlock Ack frame.

When the packet to be transmitted is not the instant reply to the packetreceived from the communication partner (step S793), the operation ofthe transmission and reception process ends without transmitting thepacket. When the packet to be transmitted is the instant reply to thepacket received from the communication partner (step S793), the controlunit 150 of the information processing device 100 transmits the packet(step S794). In this way, the packet which is the instant reply to thepacket received from the communication partner can be transmittedirrespective of the carrier sense state.

In this way, the information processing device 100 transmits the packetwhen there is a packet to be transmitted and the transmission right isacquired and when the packet to be transmitted is the instant reply tothe packet from the communication partner.

In this case, the control unit 150 of the information processing device100 transmits the packet using the physical header with the format shownin a or b of FIG. 31 based on the index of the physical header decidedin the use physical header decision process at the time of transmissionof the packet.

For example, the control unit 150 of the information processing device100 selects a modulation and communication path coding scheme by which adestination device can perform reception at a high probability accordingto the detection threshold corresponding to the decided physical headerfor the purpose of modulation used in a data portion, and performs thetransmission using the selected modulation and communication path codingscheme. For example, the control unit 150 of the information processingdevice 100 may select a modulation and communication path coding scheme(MCS) by which a destination device can perform reception at a highprobability according to the detection threshold corresponding to thedecided physical header and perform the transmission.

[Operation Example of Packet Detection and Reception DeterminationProcess]

FIG. 38 is a diagram showing an example of a relation (processclassification table) between a physical header and a process performedby the information processing device 100 according to the ninthembodiment of the present technology. FIG. 38 will be described indetail with reference to FIG. 39.

FIG. 39 is a flowchart showing a packet detection and receptiondetermination process (the processing order of step S800 shown in FIG.37) in the transmission and reception process by the informationprocessing device 100 according to the ninth embodiment of the presenttechnology.

First, the control unit 150 of the information processing device 100measures the RSSI on a signal input via the antenna 141 and retains theRSSI obtained through the measurement (step S801). The control unit 150of the information processing device 100 performs the correlationcalculation of a preamble pattern to obtain a correlator output (stepS801). The correlator output is the above-described correlation outputstrength COL. That is, the correlator output is not a normalizedcorrelator output level, but is a correlator output converted byreflecting reception power.

In this way, each of the master and slave stations corresponding to therespective functions in the ninth embodiment of the present technologyperforms measurement of the RSSI and monitoring of the correlator outputon the signal input via the antenna during the waiting state (stepS801).

Subsequently, the control unit 150 of the information processing device100 performs the correlation calculation of the pattern and compares theoutput (the correlator output) to the tentative detection threshold(step S802). Here, the tentative detection threshold is a detectionthreshold for reading the SIGNAL field before this determinationprocess. As the tentative detection threshold, for example, a valueequal to or less than both of PD_near and PD_far can be used. Forexample, PD_default can be used as the tentative detection threshold.

When the value of the correlator output is equal to or less than thetentative detection threshold (step S802), the control unit 150 of theinformation processing device 100 compares the measured RSSI to theenergy detection threshold ED (step S803). Then, the control unit 150 ofthe information processing device 100 determines whether the RSSI isgreater than the energy detection threshold ED (step S803). The energydetection threshold ED may be set to be the same as the above-describedvalue.

When the RSSI is greater than the energy detection threshold ED (stepS803), the control unit 150 of the information processing device 100retains the carrier sense BUSY state (step S804) and ends the packetdetection and reception determination process. Conversely, when the RSSIis equal to or less than the energy detection threshold ED (step S803),the control unit 150 of the information processing device 100transitions the state to a carrier sense IDLE state (step S805) and endsthe packet detection and reception determination process.

When the value of the correlator output is greater than the tentativedetection threshold (step S802), the control unit 150 of the informationprocessing device 100 determines that the state is the tentativedetection state and transitions the state to the carrier sense BUSYstate (step S806). Subsequently, the control unit 150 of the informationprocessing device 100 decodes the subsequent SIGNAL field in thephysical header to read information or the like in the SIGNAL field(step S807). Specifically, the “Link Strength Category” field, the“COLOR” field, and the cyclic redundancy check (CRC) of the physicalheader are read. As described above, the information indicating thedetection threshold to be applied is stored in the “Link StrengthCategory” field.

The control unit 150 of the information processing device 100 combinesthe read information and the process classification table shown in FIG.38 and decides a subsequent process (step S807).

Specifically, the control unit 150 of the information processing device100 calculates the CRC of the physical header to confirm whether thereis an error of the physical header. Here, when there is an error in thephysical header, validity of the value of the field may not beconfirmed. Therefore, as shown in FIG. 38, when there is an error in thephysical header, a subsequent process is decided as “reception stop(ERROR).” When there is no error in the CRC of the physical header, theprocess is decided based on content of the “Link Strength Category”field and the “COLOR” field.

Here, the control unit 150 of the information processing device 100decides the detection threshold to be applied based on “PreambleDetection Threshold” shared in the above-described physical headerparameter sharing process. Specifically, when Link Strength Category=0,the detection threshold PD_far is used. When Link Strength Category=1,the detection threshold PD_near is used. Here, when the physical headerhaving no Link Strength Category field is tentatively detected, a value(for example, PD_far) with the lowest level can be used as the detectionthreshold.

Subsequently, the control unit 150 of the information processing device100 compares the decided detection threshold to the value of thecorrelator output. When the value of the correlator output is less thanthe decided detection threshold, as shown on the upper part of FIG. 38,the subsequent process is decided as “reception stop (IDLE).” However,as shown in the upper part of FIG. 38, when there is a COLOR field andthe value of the COLOR field is the same as the value of the BSS towhich the self-device belongs, the subsequent process is exceptionallydecided as “reception.” Thus, it is possible to avoid a case in whichdetection of the packet which is originally received fails due to achange in the reception level.

Conversely, when the value of the correlator output is equal to orgreater than the decided detection threshold, as shown in the lower partof FIG. 38, the subsequent process is decided as “reception.” However,as shown in the lower part of FIG. 38, when there is a COLOR field andthe value of the COLOR field is different from the BSS to which theself-device belongs, the subsequent process is exceptionally decided as“reception stop (BUSY).” Thus, it is possible to avoid a case in whichdetection of a desired packet fails due to reception of a packet whichit is not originally necessary to receive.

In this way, the control unit 150 of the information processing device100 decides one of “reception,” “reception stop (IDLE),” “reception stop(BUSY),” and “reception step (ERROR)” as the subsequent process (stepS807).

Here, for example, when the long-distance detection threshold is used inthe case of the device in the self-BSS, a packet is assumed to arrivewith a weak level. Therefore, when the threshold (the long-distancedetection threshold) which is a comparison target is inconsistent with adetection level, the packet can be estimated to be a packet from theother BSS. In this case, the reception can be stopped. For example, whenthe long-distance detection threshold is used and the RSSI isconsiderably large, the reception can be stopped.

Accordingly, here, when there is no COLOR field and the value of thecorrelator output is equal to or greater than the decided detectionthreshold (the threshold to be applied) in the process classificationtable shown in FIG. 38, a modification example of a case in which thesubsequent process is decided as “reception” is indicated. For example,in this case, when the value of the correlator output is considerablygreater than the threshold to be applied (for example, the value of thecorrelator output is equal to or greater by a given value or more), thesubsequent process can be decided as “reception stop (BUSY)” or“reception stop (IDLE).”

For example, a case in which “Link Strength Category” in the PLCP headerdoes not provide a detection threshold with the highest level or a casein which the value of the correlator output is considerably greater thanthe decided detection threshold (the threshold to be applied) isassumed. For example, when the use physical header is decided based onbinary classification of the short distance and the long distance, thelong-distance detection threshold is a value which does not provide thedetection threshold with the highest level. In this case, when the valueof the correlator output is considerably greater than the threshold tobe applied, the threshold to be applied and the value of the correlatoroutput are considered to be large and inconsistent. This state can beinferred to be a case in which the packet transmitted from the other BSSis detected. Accordingly, in this case, since it is not necessary toperform the reception to the end, the reception can be stopped.

For example, a case in which the detection thresholds are set to first,second, and third detection thresholds in descending order is assumedwhen the use physical header is decided based on ternary classification.In this case, the second or third detection threshold is the value whichdoes not provide the detection threshold with the highest level. In thiscase, for example, when the threshold to be applied is the thirddetection threshold and the value of the correlator output is greaterthan the second detection threshold, the threshold to be applied and thevalue of the correlator output can be determined to be large andinconsistent. Similarly, for example, when the threshold to be appliedis the second detection threshold and the value of the correlator outputis greater than the first detection threshold, the threshold to beapplied and the value of the correlator output can be determined to belarge and inconsistent. This state can be inferred to be a case in whichthe packet transmitted from the other BSS is detected as in theabove-described binary case, and thus the reception can be stopped. Inparticular, when the threshold to be applied is the third detectionthreshold and the value of the correlator output is greater than thefirst detection threshold, a possibility of detection of the packettransmitted from the other BSS is considered to be high.

For example, when the packet transmitted from the other BSS is alsoestimated to be detected in a case in which the use physical header isdecided based on classification of 4 or more values, the reception canbe stopped.

Whether “reception stop (BUSY)” is set or “reception stop (IDLE)” is setcan be decided base on a comparison result between the threshold and thevalue of the correlator output. For example, a case in which the valueof the correlator output is greater than the decided detection threshold(the threshold to be applied) by a given value (for example, 20 dB ormore) is assumed to be an inconsistent treatment target. When the valueof the correlator output is greater than the threshold one step higherthan “Link Strength Category” in the PLCP header in the inconsistenttreatment, “reception stop (BUSY)” can be set. For example, when the usephysical header is decided based on the binary classification of theshort distance and the long distance, the threshold one step higher is ashort-distance detection threshold. When the value of the correlatoroutput is not greater than the threshold one step higher than “LinkStrength Category” in the PLCP header in the inconsistent treatment,“reception stop (IDLE)” can be set. For example, when the use physicalheader is decided based on the binary classification of the shortdistance and the long distance and the value of the correlator output isbetween the short-distance detection threshold and the long-distancedetection threshold, “reception stop (IDLE)” can be set.

Even when there is no COLOR information in the SIGNAL field, theclassification of the process may be set to “reception stop (IDLE)” or“reception stop (BUSY)” according to the strength of the correlatoroutput and the content of the SIGNAL field. For example, when the formatdescribed in the SIGNAL field does not correspond to the self-device,the classification of the process is normally set to “reception stop(BUSY).” Exceptionally, when the format described in the SIGNAL fielddoes not correspond to the self-device and the strength of thecorrelator output is equal to or less than a predetermined level, theclassification of the process may be set to “reception stop (IDLE).”

When “reception” is decided as the subsequent process (step S808), thecontrol unit 150 of the information processing device 100 continuouslyreceives the tentatively detected packet to the end (step S809). Whenthe received packet is destined for the self-device and an instant replyis requested, the physical header including the same “Link StrengthCategory” field as a target packet is added to be transmitted. That is,a portion in the SIGNAL field in which information regarding thedetection threshold is stored is set to be identical, and informationdecided by the self-device is stored in other portions (for example, MCSand length).

When “reception stop (BUSY)” is decided as the subsequent process (stepS808), the control unit 150 of the information processing device 100stops the reception of the tentatively detected packet at an end timepoint of the physical header and returns the state to the waiting state(step S810). Here, the carrier sense state is treated as being BUSY upto the end time of the packet (step S811). A frame interval (Inter FrameSpace (IFS)) before an attempt of subsequent transmission is set toarbitration IFS (AIFS) or distributed coordination function IFS (DIFS).

When “reception stop (IDLE)” is decided as the subsequent process (stepS808), the control unit 150 of the information processing device 100stops the reception of the tentatively detected packet at the end timepoint of the physical header and returns the state to the waiting state(step S812). Steps S807 to S812 are examples of a first procedure.

Subsequently, the control unit 150 of the information processing device100 compares the measured RSSI to the energy detection threshold ED(step S813). When the measured RSSI is greater than the energy detectionthreshold ED (step S813), the control unit 150 of the informationprocessing device 100 retains the carrier sense state as the BUSY state(step S814). The frame interval (IFS) before an attempt of subsequenttransmission is set to AIFS or DIFS.

Conversely, when the measured RSSI is equal to or less than the energydetection threshold ED (step S813), the control unit 150 of theinformation processing device 100 transitions the carrier sense state tothe IDLE state (step S815).

When the IDLE state transitions to the IDLE state (step S815 and S816)in this way, the frame interval (IFS) before an attempt of subsequenttransmission is set to AIFS (step S819). Then, a process of tracing backup to a preamble start time (or a physical header start time) of thepacket of which the reception is stopped, treating the carrier sense asIDLE, and invalidating the detection is performed (step S820).

Specifically, as in the example shown in FIG. 35, a time length (a timelength from the packet detection determination time point by thePreamble or the start time of the physical header to a current time) inwhich the physical carrier sense result is BUSY is calculated. Then, thetime slot conversion value of the length is subtracted from the backoffcounter at a time. The application of the IFS previous to the subsequentcarrier sense is also cancelled and subtraction of the backoff counterstarts instantly (step S820). When the backoff counter after thesubtraction is a negative value, as described above, for example, arandom number generated in a range between 0 and a value equal to orless than a backoff counter value before the subtraction which is set to0 and is returned to the positive absolute value of the negative valueto be used can be set to a value after the subtraction.

When “reception stop (ERROR)” is decided as the subsequent process (stepS808), the control unit 150 of the information processing device 100stops receiving the tentatively detected packet at the end time point ofthe physical header and returns the state to the waiting state (stepS812).

Subsequently, the control unit 150 of the information processing device100 compares the measured RSSI to the energy detection threshold ED(step S813). When the measured RSSI is greater than the energy detectionthreshold ED (step S813), the control unit 150 of the informationprocessing device 100 retains the carrier sense state in the BUSY state(step S814). The packet is treated as being an error and the frameinterval (IFS) before an attempt of subsequent transmission is set toextended IFS (EIFS).

Conversely, when the measured RSSI is equal to or less than the energydetection threshold ED (step S813), the control unit 150 of theinformation processing device 100 transitions the carrier sense state tothe IDLE state (step S815).

Since “reception stop (ERROR)” is decided as the subsequent process(step S816), the frame interval (IFS) before an attempt of subsequenttransmission is set to EIFS (step S817). Then, the control unit 150 ofthe information processing device 100 determines whether the correlatoroutput strength is less than a minimum detection threshold (step S818).That is, it is determined whether the correlator output strength is lessthan the minimum detection threshold in “Preamble Detection Threshold”shared in the above-described PLCP header parameter sharing process(step S818).

When the correlator output strength is less than the minimum detectionthreshold (step S818), the process proceeds to step S820. That is, thecontrol unit 150 of the information processing device 100 traces back upto the preamble start time (or the physical header start time) of thestopped packet, treats the carrier sense as IDLE, and invalidates thedetection (step S820). Steps S807, S808, S812, S813, and S815 to S820are examples of a second procedure.

In this way, it is possible to more effectively acquire the transmissionopportunity by stopping the reception and transiting to the IDLE state.

Here, when the IEEE 802.11 standard is assumed, the detection thresholdof the L-STF portion can be set as the “detection threshold” in theninth embodiment of the present technology. However, instead of thedetection threshold of the L-STF portion, the detection threshold of theL-LTE portion may be set or the detection threshold common to both ofthe L-STF portion and the L-LTF portion may be set. By independentlychanging the detection thresholds of the L-STF portion and the L-LTFportion, both of the detection thresholds may be designated as thephysical header parameters.

In this way, the control unit 150 of the information processing device100 performs control such that the reception of the packet is stoppedduring the reception according to a first condition. In this case, thecontrol unit 150 of the information processing device 100 can perform anoperation according to a second condition assuming that a carrier senseis in an idle state for a time from start of the reception of the packetto stop of the reception of the packet.

For example, a condition that the COLOR information designated in thephysical header in the received packet be different from the COLORinformation of a network belonging to the information processing device100 can be set as the first condition. For example, a condition that apreamble correlator output level of the packet during the reception inantenna input conversion be less than a packet detection thresholdderived from information described in the physical header of the packetcan be set as the first condition. In this case, the control unit 150can derive the packet detection threshold based on matching between anindex described in the physical header of the packet and a table ofthresholds shared in advance.

For example, a condition that a CRC calculation result obtained when aphysical header of the received packet is a target be identical to theCRC described in the physical header can be set as the first condition.

For example, a condition that reception power of the packet during thereception be less than a pre-decided energy detection threshold can beset as the second condition. For example, a condition that transmissionsuppression by virtual carrier sense not be applied at the time ofstopping of the reception of the packet can be set as the secondcondition.

For example, a condition related to a CRC calculation result obtainedwhen a physical header of the packet is a target and related to apreamble correlator output level in antenna input conversion can be setas the second condition. For example, a condition that a CRC calculationresult obtained when a physical header of the packet is a target not beidentical to CRC information described in the physical header and thepreamble correlator output level be less than a minimum packet detectionthreshold among applicable packet detection thresholds can be set as thesecond condition. In this case, the control unit 150 of the informationprocessing device 100 can determine necessity and non-necessity of theoperation using the second condition.

For example, when the second condition is not satisfied after stop ofthe reception of the packet, the control unit 150 of the informationprocessing device 100 prohibits transmission from the informationprocessing device 100 during a transmission continuity period of thepacket transfer. However, in this case, when the frame which is destinedfor the information processing device 100 and requests a reply isreceived, the control unit 150 may transmit the reply to the frame.

For example, the second condition may include the first condition.

When the packet detection condition is satisfied (for example, the valueof the correlator output is equal to or greater than the decideddetection threshold), the control unit 150 of the information processingdevice 100 decides the subsequent process as “reception.” However, whenthe COLOR information is present in the COLOR field and the COLORinformation is different from the COLOR information of the network towhich the information processing device 100 belongs, the subsequentprocess is decided as “reception stop (IDLE).” That is, the reception ofthe packet is stopped and the state returns to the waiting state.

For example, when the packet detection condition is not satisfied (forexample, the value of the correlator output is less than the decideddetection threshold), the control unit 150 decides the subsequentprocess as “reception stop (IDLE).” However, when the COLOR informationis present in the COLOR field and the COLOR information is identical tothe COLOR information of the network to which the information processingdevice 100 belongs, the subsequent process is decided as “reception.”That is, the packet reception process is continued.

10. Tenth Embodiment

In the fourth embodiment of the present technology, the example in whichthe plurality of Preamble sequences are defined has been described. In atenth embodiment of the present technology, as in the fourth embodimentof the preset technology, an example in which selection precision isfurther improved by defining a plurality of Preamble sequences and usingCOLOR information together will be described. The configurations ofinformation processing devices in the tenth embodiment of the presenttechnology are substantially the same as the configurations of theinformation processing devices 100 to 103, 200, and 201 shown in FIG. 1and the like. Therefore, the same reference numerals as those of thefirst embodiment of the present technology are given to common portionsto those of the first embodiment of the present technology, and thedescription thereof will be partially omitted.

The tenth embodiment of the present technology is a modification exampleof the fourth embodiment of the present technology. Therefore, some ofprocesses and formats in the tenth embodiment of the present technologyare also common portions to those of the fourth embodiment of thepresent technology. Therefore, the same reference numerals as those ofthe fourth embodiment of the present technology are given to commonportions to those of the fourth embodiment of the present technology,and the description thereof will be partially omitted.

[Example of Format of PPDU]

FIG. 40 is a diagram showing an example of the format of a PPDUexchanged between the devices included in the communication system 10according to the tenth embodiment of the present technology.

Here, the example shown in FIG. 40 is the same as the example shown inFIG. 21 except that a BSS COLOR field is set up in the SIGNAL field.Accordingly, the same reference numerals as those of FIG. 21 are givento common portions to those of FIG. 21, and the description thereof willbe partially omitted.

The PPDU is configured to include Preamble 311, SIGNAL 351, Extension303, Service 304, MPDU 305, and FCS 306.

Here, in the tenth embodiment of the present technology, a “BSS COLOR”field storing information (COLOR information) regarding a BSS identifieris set up in a part of the SIGNAL field of the physical header. In FIG.40, the “BSS COLOR” field is indicated as COLOR. BSS COLOR informationis the same as that of the ninth embodiment of the present technology.

An example of a case in which the information processing device (themaster or slave station) transmitting the physical header belongs to theBSS set to “1” as the COLOR information is shown in a and b of FIG. 40.

In this way, in the tenth embodiment of the present technology, the“COLOR” field is set up in a portion treated as being reserved in theSIGNAL 311.

The connection process is the same as the first embodiment of thepresent technology. The orders of the physical header parameter decisionprocess, the physical header parameter sharing process, and the usephysical header decision process are the same as those of the ninthembodiment of the present technology.

The transmission and reception process is the same as that of the ninthembodiment of the present technology except for the packet detection andreception determination process (the processing order of step S800 shownin FIG. 37). Accordingly, the packet detection and receptiondetermination process will be described with reference to FIGS. 41 and42.

[Operation Example of Packet Detection and Reception DeterminationProcess]

FIG. 41 is a diagram showing an example of a relation (processclassification table) between a physical header and a process performedby the information processing device 100 according to the tenthembodiment of the present technology. FIG. 41 will be described indetail with reference to FIG. 42.

FIG. 42 is a flowchart showing a packet detection and receptiondetermination process (the processing order of step S800 shown in FIG.37) in the transmission and reception process by the informationprocessing device 100 according to the tenth embodiment of the presenttechnology.

First, the control unit 150 of the information processing device 100performs measurement of the RSSI on a signal input via the antenna 141and retains the RSSI obtained through the measurement (step S821).

Subsequently, the control unit 150 of the information processing device100 compares the measured RSSI to the retained application levels (L_farand L_near) of the physical headers and decides the index of thephysical header to be applied to detection (step S822). For example, asin the selection method of selecting the transmission physical header ofthe self-device, it is possible to decide the index of the physicalheader to be applied to the detection.

For example, when the measured RSSI is compared to the value of L_nearand the measured RSSI is greater than L_near, the control unit 150 ofthe information processing device 100 decides 1 (for the short distance)as the index of the physical header to be used for the correlationdetection of the self-device. Conversely, when the measured RSSI isequal to or less than L_near, the control unit 150 of the informationprocessing device 100 decides 0 (for the long distance) as the index ofthe physical header to be used for the correlation detection of theself-device.

Subsequently, the control unit 150 of the information processing device100 performs correlation calculation using the correlator correspondingto the preamble sequence generated by the different rules, as describedabove, in the physical header with the decided index (step S823). Here,a correlator output is a correlation output strength COL as in the firstembodiment of the present technology. That is, the correlator output isnot a normalized correlator output level, but is a correlator outputconverted by reflecting reception power.

Subsequently, the control unit 150 of the information processing device100 compares the correlator output of the selected correlator to thedetection threshold of the physical header in the decided index todetermine whether the value of the correlator output is greater than thedetection threshold (step S824).

When the value of the correlator output is greater than the detectionthreshold (step S824), the control unit 150 of the informationprocessing device 100 decodes the subsequent SIGNAL field in thephysical header and reads information or the like in the SIGNAL field(step S825). Specifically, the “COLOR” field and the CRC of the physicalheader are read. The control unit 150 of the information processingdevice 100 decides one of “reception,” “reception stop (IDLE),”“reception stop (BUSY),” and “reception stop (ERROR)” as the subsequentprocess (step S825).

Specifically, the control unit 150 of the information processing device100 calculates the CRC of the physical header to confirm whether thereis an error in the physical header. Here, when there is an error in thephysical header, validity of the value of the field may not beconfirmed. Therefore, as shown in FIG. 41, when there is an error in thephysical header, a subsequent process is decided as “reception stop(ERROR).”

When there is no error in the CRC of the physical header, the process isdecided based on content of the “COLOR” field. That is, when there is noerror in the CRC of the physical header, the subsequent process isbasically decided as “reception.” However, as shown in FIG. 41, whenthere is a COLOR field and the value of the COLOR field is differentfrom the value of the BSS to which the self-device belongs, thesubsequent process is exceptionally decided as “reception stop (BUSY).”Thus, it is possible to avoid a case in which detection of a desiredpacket fails due to reception of a packet which it is not originallynecessary to receive.

A processing order (step S827) when “reception” is decided as thesubsequent process corresponds to the processing order (step S809) shownin FIG. 39. A processing order (steps S828 and S829) when “receptionstop (BUSY)” is decided as the subsequent process corresponds to theprocessing order (steps S810 and S811) shown in FIG. 39. A processingorder (steps S830 to S832) when “reception stop (IDLE)” or “receptionstop (ERROR)” is decided as the subsequent process corresponds to theprocessing order (steps S813 to S815) shown in FIG. 39.

When the value of the correlator output is equal to or less than thedetection threshold (step S824), the process proceeds to step S830. Thatis, when the value of the correlator output is equal to or less than thedetection threshold (step S824), subsequent processes are not performedand the Preamble non-detection state remains.

11. Eleventh Embodiment

In the ninth embodiment of the present technology, the example in whichthe physical header parameter decision process is performed has beendescribed. In an eleventh embodiment of the present technology, anexample in which the physical header parameter decision process isomitted will be described.

The configurations of information processing devices in the eleventhembodiment of the present technology are substantially the same as theconfigurations of the information processing devices 100 to 103, 200,and 201 shown in FIG. 1 and the like. Therefore, the same referencenumerals as those of the first embodiment of the present technology aregiven to common portions to those of the first embodiment of the presenttechnology, and the description thereof will be partially omitted.

The eleventh embodiment of the present technology is a modificationexample of the ninth embodiment of the present technology. Therefore,some of processes and formats in the eleventh embodiment of the presenttechnology are also common portions to those of the ninth embodiment ofthe present technology. Therefore, the same reference numerals as thoseof the ninth embodiment of the present technology are given to commonportions to those of the ninth embodiment of the present technology, andthe description thereof will be partially omitted.

[Example of Format of PPDU]

FIG. 43 is a diagram showing an example of the format of a PPDUexchanged between the devices included in the communication system 10according to the eleventh embodiment of the present technology.

Here, the example shown in FIG. 43 is the same as the example shown inFIG. 31 except that “Requested Detection Level” is set up in the SIGNALfield instead of “Link Strength Category.” Accordingly, the samereference numerals as those of FIG. 31 are given to common portions tothose of FIG. 31, and the description thereof will be partially omitted.

The PPDU is configured to include Preamble 301, SIGNAL 361, Extension303, Service 304, MPDU 305, and FCS 306.

Here, in the eleventh embodiment of the present technology, a “RequestedDetection Level” field and a “BSS COLOR” field storing COLOR informationare set up in parts of the SIGNAL field of the physical header.

When the “Requested Detection Level” field in the SIGNAL field of thephysical header is set up in this way, the information processing devicecan directly designate a signal level desired to be used for thedetection determination in regard to destinations at the time oftransmission. Here, a quantization method and a unit of the signal levelare assumed to be shared between the destinations.

Each information processing device changes content of the “RequestedDetection Level” field according to quality of link with thedestination.

In this way, in the eleventh embodiment of the present technology, the“Requested Detection Level” field and the “COLOR” field are set up inportions treated as being reserved in the SIGNAL 361. Thus, it ispossible to realize a specific function in the eleventh embodiment ofthe present technology without interfering with reception of the legacydevice.

The information processing device (other than the legacy device)receiving the packet including the “Requested Detection Level” field canacquire the content of the “Requested Detection Level” field. Then, theinformation processing device can directly use the content of the“Requested Detection Level” field as the detection threshold to beapplied.

The connection process is the same as that of the first embodiment ofthe present technology. The physical header parameter decision processcan be omitted, as described above.

In the eleventh embodiment of the present technology, exchange of infonation between the master and slave stations in regard to the detectionapplication threshold can be omitted. Therefore, the physical headerparameter sharing process can be omitted. In the eleventh embodiment ofthe present technology, however, information regarding “COLOR” (the BSSidentifier in the physical layer) and “TxPower” (transmission power ofthe master station) is also additionally transferred in addition to“Multi Detect Parameter.” An example of the frame format used in thiscase is shown in FIG. 44.

[Example of Beacon Frame Format]

FIG. 44 is a diagram showing an example of a beacon frame formatexchanged between the devices included in a communication system 10according to the eleventh embodiment of the present technology. SinceFIG. 44 is a modification example of FIG. 32, the same referencenumerals as those of FIG. 32 are given to common portions to those ofFIG. 32, and the description thereof will be partially omitted.

FIG. 44 illustrates an example in which “Multi Detect Parameter” 311 isomitted in Payload 340 shown in FIG. 32. “COLOR Info” 371 and “TxPowerInfo” 372 correspond to “COLOR Info” 341 and “TxPower Info” 342 shown inFIG. 32.

For example, the control unit of the information processing device 200transmits a beacon in which information is stored in “COLOR Info” 371and “TxPower Info” 372 to nearby information processing devices toinform the nearby information processing devices of the beacon.

The information processing device informed of the beacon acquires theinformation stored in “COLOR Info” 371, and “TxPower Info” 372 from thebeacon to retain the information. That is, the information processingdevice retains content of the BSS identifier in the physical layer andthe transmission power of a communication partner (for example, themaster station).

When the content of the beacon is retained and subsequently informationincluded in a subsequent beacon is changed, information included in alatest beacon (latest information) is adopted and retained.

The master station may notify of the content of the BSS identifier inthe physical layer and the transmission power of the self-device using asignal other than the beacon transmission. For example, the masterstation may perform the notification using a unicast data frame ormanagement frame to a subordinate terminal using determination by theself-device or an information acquisition request from the subordinateterminal as a trigger.

[Operation Example of Use Physical Header Decision Process]

FIG. 45 is a flowchart showing an example of a processing order of a usephysical header decision process (transmission physical header selectionprocess) by the information processing device 100 according to theeleventh embodiment of the present technology.

First, the control unit 150 of the information processing device 100monitors packets received from destinations connected to the self-deviceand acquires the RSSI of each destination (step S841). The RSSI (themonitoring result (the RSSI measurement result for each destination))acquired in this way is set to RSSI_peer. In the eleventh embodiment ofthe present technology, RSSI information from the master station towhich the information processing device 100 is connected can be set toRSSI_peer.

When measured values of the packets received from the destinationsconnected to the self-device are retained, the control unit 150 of theinformation processing device 100 may read the measured value to acquirethe RSSI of each destination (step S841).

Here, in the case of the information processing device (for example, theinformation processing device 100) connected to the master station (forexample, the information processing device 200), only the master stationis basically set as the destination. In this case, the reception levelof a previous beacon may be used as a monitoring result.

Subsequently, the control unit 150 of the information processing device100 corrects the acquired RSSI_peer in consideration of a transmissionpower difference (step S842). For example, “TxPower” information (whichis stored in “TxPower Info” 372 shown in FIG. 44) notified of with thebeacon by the master station is set to TP_peer. Transmission power usedfor transmission to the master station by the information processingdevice 100 is set to TP_self. In this case, the corrected RSSI_adjustedcan be obtained by the following Expression 13 (which is the same asExpression 13 in the ninth embodiment of the present technology).

RSSI_adjusted=RSSI_peer+(TP_self−TP_peer)  Expression 13

Here, RSSI_adjusted indicates an estimated value of the RSSI expectedwhen the master station side receives transmission from the informationprocessing device 100. However, when information corresponding toTP_peer may not be obtained, RSSI_adjusted may be substituted withRSSI_peer.

Subsequently, the control unit 150 of the information processing device100 converts RSSI_adjusted into an application desired detection levelLreq using the following Expression 15. Here, Expression 15 isdescription in which calculation in logarithm (dB) is assumed.

L_req=RSSI_adjusted+O  Expression 15

Here, O is an offset amount of a margin for a preamble detection errorby a variation in a reception level. For example, O can be set to arange of about −10 dBm to −20 dBm.

A value of the application desired detection level L_req obtained inthis way is quantized in predetermined units shared in advance to bestored in the “Requested Detection Level” field 361 (which is a portionof “xx” shown in FIG. 43).

The example in which the RSSI is used has been described in FIG. 45.However, the correlation output strength COL may be used instead of theRSSI.

[Operation Example of Transmission and Reception Process]

A transmission and reception process is substantially the same as thatof the ninth embodiment of the present technology and only a processclassification table of the physical header after tentative detection isdifferent. Accordingly, an example of the process classification tableused in the eleventh embodiment of the present technology is shown inFIG. 46.

FIG. 46 is a diagram showing an example of a relation (processclassification table) between a physical header and a process performedby the information processing device 100 according to the eleventhembodiment of the present technology.

In the ninth embodiment of the present technology, the example in whichthe application detection threshold is acquired from the threshold listretained in advance using “Link Strength Category” has been described.However, in the eleventh embodiment of the present technology, adetection threshold to be applied is directly described in the“Requested Detection Level” field. Therefore, in the eleventh embodimentof the present technology, the detection threshold (the applicationdesired detection level Lreq) described in the “Requested DetectionLevel” field can be used without change.

In this way, the process classification table in the eleventh embodimentof the present technology is different from the process classificationtable (shown in FIG. 38) in the ninth embodiment of the presenttechnology in the detection threshold to be applied. The other remainingprocesses are the same as those of the ninth embodiment of the presenttechnology, and thus the description thereof will be omitted.

12. Twelfth Embodiment

In the first embodiment of the present technology, the example in whichLink Strength Category field is set up in the SIGNAL field of the IEEE802.11 standard has been described.

In a twelfth embodiment of the present technology, an example in whichthe Link Strength Category field is not set up in the SIGNAL field ofthe IEEE 802.11 standard and a field storing information regarding a BSSidentifier is set up will be described. In the twelfth embodiment of thepresent technology, an example in which a packet is selected with onlythe BSS identifier will be described. The configurations of informationprocessing devices in the twelfth embodiment of the present technologyare substantially the same as the configurations of the informationprocessing devices 100 to 103, 200, and 201 shown in FIG. 1 and thelike. Therefore, the same reference numerals as those of the firstembodiment of the present technology are given to common portions tothose of the first embodiment of the present technology, and thedescription thereof will be partially omitted.

Some of the processes and the formats in the twelfth embodiment of thepresent technology are common to those of the first embodiment of thepresent technology. Therefore, the same reference numerals as those ofthe first embodiment of the present technology are given to commonportions to those of the first embodiment of the present technology, andthe description thereof will be partially omitted.

[Example of Format of PPDU]

FIG. 47 is a diagram showing an example of the format of a PPDUexchanged between the devices included in the communication system 10according to the twelfth embodiment of the present technology.

Here, the example shown in FIG. 47 is the same as the example shown inFIG. 7 except that the BSS COLOR field is set up in the SIGNAL fieldrather than Link Strength Category field. Accordingly, the samereference numerals as those of FIG. 7 are given to common portions tothose of FIG. 7, and the description thereof will be partially omitted.

The PPDU is configured to include Preamble 301, SIGNAL 381, Extension303, Service 304, MPDU 305, and FCS 306.

In the twelfth embodiment of the present technology, the “BSS COLOR”field storing information (COLOR information) regarding the BSSidentifier is set up in a part of the SIGNAL field of the physicalheader. In FIG. 47, the “BSS COLOR” field is indicated by COLOR.

An example of a case in which an information processing device (masteror slave station) transmitting the physical header belongs to the BSS inwhich “1” is set as the COLOR information (that is, COLOR=1) is shown ina of FIG. 47. Here, b of FIG. 47 corresponds to c of FIG. 7.

In this way, in the twelfth embodiment of the present technology, a“COLOR” field is set up in the SIGNAL 311. When there is a portiontreated as being reserved in the SIGNAL field with the existing format,it is possible to realize a specific function in the twelfth embodimentof the present technology without interfering with reception of thelegacy device by storing the COLOR field in that portion. When theformat of the SIGNAL field is newly defined, the COLOR information isstored in that portion.

The information processing device (other than the legacy device)receiving the packet including the COLOR field can acquire content ofthe COLOR field. Then, based on the content of the COLOR field, theinformation processing device can change the reception operation and thedetection threshold to be applied.

[Example of Connection Process]

A connection process is the same as that of the first embodiment of thepresent technology.

[Operation Example of Physical Header Parameter Decision Process]

FIG. 48 is a flowchart showing an example of a processing order of aphysical header parameter decision process by the information processingdevice 200 according to the twelfth embodiment of the presenttechnology.

When connection is established, the control unit of the informationprocessing device 200 generates physical header parameters (for example,detection thresholds of the physical header) to be used by subordinateterminals and the self-device in the self-BSS (updates the physicalheader parameters when the parameters are already present).Specifically, a difference in the physical header in the twelfthembodiment of the present technology is a difference in matching ornon-matching of the BSS identifier information (COLOR information) inthe physical header with information of the BSS to which the self-devicebelongs.

First, the control unit of the information processing device 200performs packet monitoring (step S841). Then, the control unit of theinformation processing device 200 acquires information regardingcommunication quality with each subordinate information processingdevice in the self-BSS and information regarding communication qualityof packets from other BSSs (OBSSs) (step S841).

Here, an example in which RSSI or correlation output strength of thePLCP preamble is used as an index of the communication quality will bedescribed. The correlation output strength is not a correlator output inwhich power is normalized, but is assumed to indicate an absolute levelobtained by multiplying a correlator output by a RSSI. That is, thecorrelation output strength is a correlator output corrected to anantenna input conversion. When there is a reception history at arelatively close time, a record of the correlation output strength atthat time may be properly used. At the time of monitoring, the detectionthreshold may be temporarily lowered so that a more reliable sample iscollected.

Subsequently, the control unit of the information processing device 200classifies communication quality of packets received from thesubordinate information processing devices in the self-BSS andcommunication quality of packets received from the other BSS (OBSS)(step S842). Then, the control unit of the information processing device200 extracts a minimum correlation output strength in regard to theself-BSS and a maximum correlation output strength in regard to the OBSS(step S842).

Here, the minimum correlation output strength in regard to the self-BSSis a minimum correlation output strength of a packet for which the BSSidentifier (the BSSID in the MAC header or the BSS COLOR information inthe physical header) is the same as that of the BSS to which theself-device belongs and is set to COL_self. Further, the maximumcorrelation output strength in regard to the OBSS is a maximumcorrelation output strength of a packet for which the BSS identifier(the BSSID in the MAC header or the BSS COLOR information in thephysical header) is different from that of the BSS to which theself-device belongs and is set to COL_other.

COL for which there is no packet sample of a corresponding condition isreplaced with PD_default. Here, PD_default indicates a reference levelof preamble detection used by a legacy device. In the IEEE 802.11standard, as a standard value, a value such as −82 dBm every 20 MHzbandwidth is referred to.

Subsequently, the control unit of the information processing device 200decides a detection threshold PD_self for the physical header indicatingthe self-BSS and a detection threshold PD_other for the physical headerindicating the OBSS based on the extracted correlation output strengths(step S843). For example, the detection threshold PD_self and thedetection threshold PD_other can be decided in a range in whichrelations of the following Expressions 16, 17, and 18 are established.The decision of PD_self may be omitted. In this case, PD_self issubstituted with PD_default.

PD_self<COL_self  Expression 16

PD_other<COL_other  Expression 17

PD_other<COL_self  Expression 18

In this case, when there is no PD_other which simultaneously satisfiesExpression 17 and 18, Expression 18 is preferred.

PD_other may be individually decided for each subordinate informationprocessing device. An index of the information processing device is setto n and PD_other to be used by an n-th subordinate informationprocessing device is set to PD_other(n). The control unit of theinformation processing device 200 classifies the packets transmittedfrom the subordinate information processing devices in the self-BSS inthe above-described monitoring result for each transmission source. Whenthe minimum correlation output strength obtained from the packet fromthe n-th subordinate information processing device is set toCOL_self(n), PD_other(n) is decided so that the following Expression 19is satisfied.

PD_other(n)<COL_self(n)  Expression 19

Even when PD_other is individually decided, PD_other(n) may notnecessarily be designated in all of the subordinate devices. In thiscase, information regarding common PD_other to be used by the deviceswhich are not individually designated is additionally decided.

Here, an example of a carrier sense detection range of each informationprocessing device set based on the detection threshold PD_self and thedetection threshold PD_other(n) will be described. Here, examples of thecarrier sense detection ranges of the information processing devices100, 102, 200, and 201 will be described with reference to FIGS. 12 and13.

As described above, in FIG. 12, carrier sense detection ranges 31 to 34of the information processing devices 100 and 102 are schematicallyindicated by dotted circles. In FIG. 13, carrier sense detection ranges41 to 44 of the information processing devices 200 and 201 areschematically indicated by dotted circles.

For example, in FIG. 12, the carrier sense detection range 31corresponds to a carrier sense detection range of the informationprocessing device 100 set based on the detection threshold PD_self forthe physical header indicating the self-BSS of the informationprocessing device 100. Further, the carrier sense detection range 33corresponds to a carrier sense detection range of the informationprocessing device 100 set based on the detection threshold PD_other(n)for the physical header indicating the OBSS of the informationprocessing device 100.

In FIG. 12, the carrier sense detection range 32 indicates a carriersense detection range of the information processing device 102 set basedon the detection threshold PD_self for the physical header indicatingthe self-BSS of the information processing device 102. Further, thecarrier sense detection range 34 corresponds to a carrier sensedetection range of the information processing device 102 set based onthe detection threshold PD_other(n) for the physical header indicatingthe OBSS of the information processing device 102.

In FIG. 13, the carrier sense detection range 41 corresponds to acarrier sense detection range of the information processing device 200set based on the detection threshold PD_self for the physical headerindicating the self-BSS of the information processing device 200.Further, the carrier sense detection range 43 corresponds to a carriersense detection range of the information processing device 200 set basedon the detection threshold PD_other(n) for the physical headerindicating the OBSS of the information processing device 200.

In FIG. 13, the carrier sense detection range 42 indicates a carriersense detection range of the information processing device 201 set basedon the detection threshold PD_self for the physical header indicatingthe self-BSS of the information processing device 201. Further, thecarrier sense detection range 44 corresponds to a carrier sensedetection range of the information processing device 201 set based onthe detection threshold PD_other(n) for the physical header indicatingthe OBSS of the information processing device 201.

The monitoring and the decision of the setting values shown in FIG. 48may be performed for each given time or may be performed wheneverconnection of a new subordinate device is detected, so that the settingvalues can be updated sequentially.

[Example of Physical Header Parameter Sharing Process]

The order of a physical header parameter sharing process is the same asthat of the first embodiment of the present technology. In the twelfthembodiment of the present technology, however, the physical headerparameters are detection thresholds (the detection threshold PD_self ofthe physical header for the self-BSS and the detection thresholdPD_other of the physical header for the OBSS). An example of the frameformat used in this case is shown in FIG. 49.

[Example of Beacon Frame Format]

FIG. 49 is a diagram showing an example of a beacon frame formatexchanged between the devices included in a communication system 10according to the twelfth embodiment of the present technology. SinceFIG. 49 is a modification example of FIG. 14, the description of commonportions to those of FIG. 14 will be partially omitted.

FIG. 49 shows an example in which elements such as “Multi DetectParameter” 391 and “COLOR info” 392 are newly added to Payload 390.

Three fields 393 to 395 are set up in “Multi Detect Parameter” 391.

The detection threshold PD_self of the physical header of the self-BSSis stored in Preamble Detection Threshold for Packets of This BSS 393.The detection threshold PD_other of the physical header for the OBSS isstored in Preamble Detection Threshold for Packets of OBSS 394. Here, itis necessary to store the detection threshold PD_other of the physicalheader OBSS, but the detection threshold of the physical header for theself-BSS may not be stored. In this way, when the detection threshold ofthe physical header for the self-BSS is not stored, each informationprocessing device can substitute the detection threshold asPD_self=PD_default. When PD_other can be individually decided for eachsubordinate information processing device in the above-describedphysical header parameter decision process (that is, PD_other(n) isdecided), information regarding all PD_other(n) is stored in this fieldalong with information for specifying the subordinate devicecorresponding to the information. When PD_other(n) is not designated inregard to any of the subordinate devices, information regarding PD_othercommonly used by undesignated devices is also stored.

Information indicating whether reception stop is permitted in regard toa packet not including BSS COLOR is stored in Allow No Color Filtering395. Whether to permit the reception stop can be set, for example,according to a device connected to the information processing device200. For example, when only one device (for example, a legacy device)for which the COLOR information may not be added is not present insubordination to the information processing device 100, the control unitof the information processing device 200 can perform setting such thatthe reception step is permitted.

In regard to the information stored in Allow No Color Filtering 395,this field may be substituted with another field, when the field can besubstituted with the other field. In this way, when the field issubstituted with another field, information to be stored in Allow NoColor Filtering 395 may not be stored in “Multi Detect Parameter.”

The BSS identifier in the physical layer is stored in “COLOR Info” 392.The BSS identifier corresponds to the BSS identifier stored in the “BSSCOLOR” field shown in FIG. 47.

For example, the control unit of the information processing device 200transmits a beacon in which information is stored in “Multi DetectParameter” 391 and “COLOR Info” 392 to nearby information processingdevices to inform the nearby information processing devices of thebeacon.

The information processing device informed of the beacon acquires theinformation stored in “Multi Detect Parameter” 391 and “COLOR Info” 392from the beacon to retain the information. That is, the informationprocessing device retains content of “Multi Detect Parameter” and theBSS identifier in the physical layer. When PD_other to be used by theinformation processing device is individually designated, PD_other(n)corresponding to the self-device is assumed to be retained as the valueof PD_other. When PD_other is not individually designated, the value ofPD_other to be commonly used by the subordinate devices is retained.

When the content of the beacon is retained and subsequently informationincluded in a subsequent beacon is changed, information included in alatest beacon (latest information) is adopted and retained.

The master station may notify of the content of “Multi Detect Parameter”and the BSS identifier in the physical layer using a signal other thanthe beacon transmission. For example, the master station may perform thenotification using a unicast data frame or management frame to asubordinate terminal using determination by the self-device or aninformation acquisition request from the subordinate terminal as atrigger.

[Example of Use Physical Header Decision Process]

In the twelfth embodiment of the present technology, BSS COLORinformation to be used in the self-BSS is added to the physical header.The PLCP header is not changed according to a link state. The usephysical header decision process is performed in the same way in anuplink and a downlink.

[Example of Transmission and Reception Process]

The order of a transmission and reception process according to thetwelfth embodiment of the present technology is the same as that of theninth embodiment of the present technology (the transmission andreception process shown in FIG. 37). For example, both of the master andslave station sides can perform the transmission and reception processshown in FIG. 37 in the same way. For example, both of the master andslave station sides are assumed to perform a packet detection andreception determination process basically for a time other than duringtransmission and reception.

[Operation Example of Packet Detection and Reception DeterminationProcess]

The packet detection and reception determination process according tothe twelfth embodiment of the present technology is basically the sameas that of the ninth embodiment (the operation example shown in FIG. 39)of the present technology. However, a process classification table to bereferred to is different.

FIG. 50 is a diagram showing an example of a relation (processclassification table) between a physical header and a process performedby the information processing device 100 according to the twelfthembodiment of the present technology. FIG. 50 will be described indetail with reference to FIG. 39.

As shown in FIG. 39, each of the master and slave stations correspondingto the respective functions in the twelfth embodiment of the presenttechnology performs measurement of the RSSI and monitoring of thecorrelator output on the signal input via the antenna during the waitingstate (step S801).

Subsequently, the control unit 150 of the information processing device100 performs the correlation calculation of the Preamble pattern andcompares the output (the correlator output) to the tentative detectionthreshold (step S802). Here, the tentative detection threshold is adetection threshold for reading the SIGNAL field before thisdetermination process. As the tentative detection threshold, forexample, a value equal to or less than both of PD_self and PD_other canbe used. For example, PD_default can be used as the tentative detectionthreshold.

The “correlator output” mentioned herein means the above-describedcorrelation output strength COL. The correlator output is not anormalized correlator output level, but is a correlator output convertedby reflecting reception power.

When the value of the correlator output is greater than the tentativedetection threshold (step S802), the control unit 150 of the informationprocessing device 100 determines that the state is the tentativedetection state and transitions the state to the carrier sense BUSYstate (step S806). Subsequently, the control unit 150 of the informationprocessing device 100 decodes the subsequent SIGNAL field in thephysical header to read information or the like in the SIGNAL field(step S807). Specifically, the “COLOR” field and the CRC of the physicalheader are read.

The control unit 150 of the information processing device 100 combinesthe read information and the process classification table shown in FIG.50 and decides a subsequent process (step S807).

Specifically, the control unit 150 of the information processing device100 calculates the CRC of the physical header to confirm whether thereis an error in the physical header. Here, when there is an error in thephysical header, validity of the value of the field may not beconfirmed. Therefore, as shown in FIG. 50, when there is an error in thephysical header, a subsequent process is decided as “reception stop(ERROR).” When there is no error in the CRC of the physical header, theprocess is decided based on content of the “COLOR” field and theinformation shared in the physical header parameter sharing process.

Specifically, when the COLOR information in the physical header isidentical to the COLOR information of the self-BSS, the subsequentprocess is decided as “reception.”

When the COLOR information in the physical header is different from theCOLOR information of the self-BSS, the control unit 150 of theinformation processing device 100 compares the decided detectionthreshold to the value of the correlator output.

When the COLOR information in the physical header is different from theCOLOR information of the self-BSS and the value of the correlator outputis lower on the basis of the detection threshold PD_other for thephysical header indicating the OBSS, the subsequent process is decidedas “reception stop (IDLE).”

Further, when the COLOR information in the physical header is differentfrom the COLOR information of the self-BSS and the value of thecorrelator output is higher on the basis of the detection thresholdPD_other for the physical header, the subsequent process is decided as“reception stop (BUSY).”

The case in which the value of the correlator output is lower on thebasis of the detection threshold PD_other is a case in which the valueof the correlator output is equal to or less than the detectionthreshold PD_other or a case in which the value of the correlator outputis less than the detection threshold PD_other. The case in which thevalue of the correlator output is higher on the basis of the detectionthreshold PD_other is a case in which the value of the correlator outputis equal to or greater than the detection threshold PD_other or a casein which the value of the correlator output is greater than thedetection threshold PD_other. When the case in which the value of thecorrelator output is lower on the basis of the detection thresholdPD_other is set to the case in which the value of the correlator outputis equal to or less than the detection threshold PD_other, the case inwhich the value of the correlator output is higher on the basis of thedetection threshold PD_other is set to the case in which the value ofthe correlator output is greater than the detection threshold PD_other.Similarly, when the case in which the value of the correlator output islower on the basis of the detection threshold PD_other is set to thecase in which the value of the correlator output is less than thedetection threshold PD_other, the case in which the value of thecorrelator output is higher on the basis of the detection thresholdPD_other is set to the case in which the value of the correlator outputis equal to or greater than the detection threshold PD_other.

When there is no COLOR information in the physical header, thesubsequent process is decided as “reception.” Exceptionally, the samedetermination as that of the case of the COLOR mismatch described aboveis performed only when the reception stop of the packet in which theCOLOR information is not included is permitted in the BSS. Whether topermit the reception stop can be determined based on information storedin Allow No COLOR Filtering 395 shown in FIG. 49.

The other remaining processes are the same as those of the ninthembodiment of the present technology, and thus the description thereofwill be omitted herein.

As described above, for example, the condition that the preamblecorrelator output level of the packet during the reception in theantenna input conversion be less than the packet detection thresholdderived from the information described in the physical header of thepacket can be set as the first condition. In this case, the control unit150 can perform the derivation through conversion based on a valuedescribed in the physical header of the packet and information regardinga unit and quantization shared in advance.

In the embodiments of the present technology, the communication systemincluding the access points (the information processing devices 200 and201) has been described as an example, but the embodiments of thepresent technology can also be applied to a communication systemincluding no access point. Examples of the communication systemincluding no access point include a mesh network or an ad-hoc network.

For example, when quality of link with another information processingdevice that is not connected to the self-device is confirmed, a packetdetection condition (a detection threshold of PLCP) in which a conditionis relaxed most may be used in a period of time in which a reply isexpected.

Here, when the number of slave stations increases in a CSMACA network,excessive transmission suppression occurs, and thus a situation in whichtransmission efficiency of an entire system deteriorates may happen inthe carrier sense scheme. Accordingly, there is a method of increasingtransmission opportunities by raising the detection threshold of thecarrier sense. However, when a reception side terminal first receives anunrelated packet despite an increase in the number of transmissionopportunities on a transmission side, a reception opportunity may belost. For this reason, it is necessary for the reception side toappropriately raise the detection threshold.

However, in an information processing device (for example, an accesspoint) for which a plurality of connection partners asynchronouslyperforming transmission to the self-device are simultaneously present,it is assumed that it is difficult to optimally set a detectionthreshold in advance. For example, when the threshold is set to benormally high, a service area may be narrowed, and thus there is aconcern of communication not being appropriately performed with some ofthe plurality of connection partners.

Accordingly, in an embodiment of the present technology, a plurality ofphysical headers to be used properly according to attenuation fromdestinations are defined and different detection thresholdscorresponding to the physical headers are prepared. Thus, it is possibleto appropriately change a detection operation according to acommunication partner. That is, according to an embodiment of thepresent technology, it is possible to avoid excessive transmissionsuppression as necessary, increase both transmission opportunities andreception opportunities, and improve use efficiency of radio resources.In other words, it is possible to efficiently use radio resources inchannel access for wireless transmission.

13. Application Examples

The technology according to the present disclosure can be applied tovarious products. For example, the information processing devices 100 to104, 200, and 201 may be realized as mobile terminals such assmartphones, tablet personal computers (PCs), notebook PCs, portablegame terminals, or digital cameras, fixed-type terminals such astelevision receivers, printers, digital scanners, or network storages,or car-mounted terminals such as car navigation devices. Further, theinformation processing devices 100 to 104, 200, and 201 may be realizedas terminals (also referred to as machine type communication (MTC)terminals) which perform machine to machine (M2M) communication, such assmart meters, vending machine, remote monitoring devices and point ofsale (POS) terminals. Furthermore, the information processing devices100 to 104, 200, and 201 may be wireless communication modules mountedin such terminals (for example, integrated circuit modules configured inone die).

For example, the information processing devices 200, and 201 may berealized as a wireless LAN access point (which is also referred to as awireless base station) that has no router function or has a routerfunction. The information processing devices 200, and 201 may berealized as a mobile wireless LAN router. Furthermore, the informationprocessing devices 200, and 201 may be wireless communication modulesmounted in such devices (for example, integrated circuit modulesconfigured in one die).

13-1. First Application Example

FIG. 51 is a block diagram showing an example of a schematicconfiguration of a smartphone 900 to which the technology of the presentdisclosure can be applied. The smartphone 900 includes a processor 901,a memory 902, a storage 903, an externally connected interface 904, acamera 906, a sensor 907, a microphone 908, a input device 909, adisplay device 910, a speaker 911, a wireless communication interface913, an antenna switch 914, an antenna 915, a bus 917, a battery 918,and an auxiliary controller 919.

The processor 901 may be, for example, a central processing unit (CPU)or a system on chip (SoC), and controls functions of an applicationlayer and other layers of the smartphone 900. The memory 902 includes arandom access memory (RAM) and a read only memory (ROM), and storesprograms executed by the processor 901 and data. The storage 903 caninclude a storage medium such as a semiconductor memory or a hard disk.The externally connected interface 904 is an interface for connecting anexternally attached device such as a memory card or a universal serialbus (USB) device to the smartphone 900.

The camera 906 has an image sensor, for example, a charge coupled device(CCD) or a complementary metal oxide semiconductor (CMOS) to generatecaptured images. The sensor 907 can include a sensor group including,for example, a positioning sensor, a gyro sensor, a geomagnetic sensor,an acceleration sensor, and the like. The microphone 908 converts soundsinput to the smartphone 900 into audio signals. The input device 909includes, for example, a touch sensor that detects touches on a screenof the display device 910, a key pad, a keyboard, buttons, switches, andthe like to receive manipulations or information inputs from a user. Thedisplay device 910 has a screen such as a liquid crystal display (LCD),or an organic light emitting diode (OLED) display to display outputimages of the smartphone 900. The speaker 911 converts audio signalsoutput from the smartphone 900 into sounds.

The wireless communication interface 913 supports one or more wirelessLAN standards of IEEE 802.11a, 11b, 11g, 11n, 11ac, and 11ad to executethe wireless LAN communication. The wireless communication interface 913can communicate with another apparatus via a wireless LAN access pointin an infrastructure mode. In addition, the wireless communicationinterface 913 can directly communicate with another apparatus in adirect communication mode such as an ad hoc mode, Wi-Fi Direct, or thelike. Wi-Fi Direct is different from the ad hoc mode, and thus one oftwo terminals operates as an access point. However, communication isperformed directly between the terminals. The wireless communicationinterface 913 can typically include a baseband processor, a radiofrequency (RF) circuit, a power amplifier, and the like. The wirelesscommunication interface 913 may be a single-chip module on which amemory that stores a communication control program, a processor thatexecutes the program, and a relevant circuit are integrated. Thewireless communication interface 913 may support another kind ofwireless communication scheme such as a cellular communication scheme, ashort-range wireless communication scheme, or a proximity wirelesscommunication scheme in addition to the wireless LAN scheme. The antennaswitch 914 switches a connection destination of the antenna 915 for aplurality of circuits (for example, circuits for different wirelesscommunication schemes) included in the wireless communication interface913. The antenna 915 has a single or a plurality of antenna elements(for example, a plurality of antenna elements constituting a MIMOantenna), and is used for transmission and reception of wireless signalsfrom the wireless communication interface 913.

Note that the smartphone 900 may include a plurality of antennas (forexample, antennas for a wireless LAN or antennas for a proximitywireless communication scheme, or the like), without being limited tothe example of FIG. 51. In this case, the antenna switch 914 may beomitted from the configuration of the smartphone 900.

The bus 917 connects the processor 901, the memory 902, the storage 903,the externally connected interface 904, the camera 906, the sensor 907,the microphone 908, the input device 909, the display device 910, thespeaker 911, the wireless communication interface 913, and the auxiliarycontroller 919 to one another. The battery 918 supplies electric powerto each of the blocks of the smartphone 900 shown in FIG. 51 via powersupply lines partially indicated by dashed lines in the drawing. Theauxiliary controller 919 causes, for example, required minimum functionsof the smartphone 900 to be operated in a sleep mode.

In the smartphone 900 shown in FIG. 51, the control unit 150 describedwith reference to FIG. 5 may be mounted on the wireless communicationinterface 913. At least some of the functions may be mounted on theprocessor 901 or the auxiliary controller 919. For example, saving radioresources by grouping can reduce the power consumption of the battery918.

The smartphone 900 may operate as a wireless access point (software AP)when the processor 901 performs an access point function at anapplication level. The wireless communication interface 913 may have thewireless access point function.

13-2. Second Application Example

FIG. 52 is a block diagram showing an example of a schematicconfiguration of a car navigation apparatus 920 to which the technologyof the present disclosure can be applied. The car navigation apparatus920 includes a processor 921, a memory 922, a global positioning system(GPS) module 924, a sensor 925, a data interface 926, a content player927, a storage medium interface 928, an input device 929, a displaydevice 930, a speaker 931, a wireless communication interface 933, anantenna switch 934, an antenna 935, and a battery 938.

The processor 921 may be, for example, a CPU or an SoC controlling anavigation function and other functions of the car navigation apparatus920. The memory 922 includes a RAM and a ROM storing programs executedby the processor 921 and data.

The GPS module 924 measures a position of the car navigation apparatus920 (for example, latitude, longitude, and altitude) using GPS signalsreceived from a GPS satellite. The sensor 925 can include a sensor groupincluding, for example, a gyro sensor, a geomagnetic sensor, abarometric sensor, and the like. The data interface 926 is connected toan in-vehicle network 941 via, for example, a terminal that is notillustrated to acquire data generated on the vehicle side such as carspeed data.

The content player 927 reproduces content stored in a storage medium(for example, a CD or a DVD) inserted into the storage medium interface928. The input device 929 includes, for example, a touch sensor thatdetects touches on a screen of the display device 930, buttons,switches, and the like to receive manipulations or information inputsfrom a user. The display device 930 has a screen such as an LCD or anOLED display to display images of the navigation function or reproducedcontent. The speaker 931 outputs sounds of the navigation function orreproduced content.

The wireless communication interface 933 supports one or more wirelessLAN standards of IEEE 802.11a, 11b, 11g, 11n, 11ac, and 11ad to executewireless LAN communication. The wireless communication interface 933 cancommunicate with another apparatus via a wireless LAN access point inthe infrastructure mode. In addition, the wireless communicationinterface 933 can directly communicate with another apparatus in adirect communication mode, such as an ad hoc mode, Wi-Fi Direct, or thelike. The wireless communication interface 933 can typically have abaseband processor, an RF circuit, a power amplifier, and the like. Thewireless communication interface 933 may be a single-chip module onwhich a memory that stores a communication control program, a processorthat executes the program, and a relevant circuit are integrated. Thewireless communication interface 933 may support another kind ofwireless communication scheme such as a short-range wirelesscommunication scheme, a proximity wireless communication scheme, or thecellular communication scheme in addition to the wireless LAN scheme.The antenna switch 934 switches a connection destination of the antenna935 for a plurality of circuits included in the wireless communicationinterface 933. The antenna 935 has a single or a plurality of antennaelements and is used for transmission and reception of wireless signalsfrom the wireless communication interface 933.

Note that the car navigation apparatus 920 may include a plurality ofantennas, without being limited to the example of FIG. 52. In this case,the antenna switch 934 may be omitted from the configuration of the carnavigation apparatus 920.

The battery 938 supplies electric power to each of the blocks of the carnavigation apparatus 920 shown in FIG. 52 via power supply linespartially indicated by dashed lines in the drawing. In addition, thebattery 938 accumulates electric power supplied from the vehicle.

In the car navigation apparatus 920 shown in FIG. 52, the control unit150 described with reference to FIG. 5 may be mounted on the wirelesscommunication interface 933. At least some of the functions may bemounted on the processor 921.

The wireless communication interface 933 may operate as theabove-described information processing device 100 to provide wirelessconnection to a terminal carried by a user in a vehicle.

The technology of the present disclosure may be realized as anin-vehicle system (or a vehicle) 940 including one or more blocks of theabove-described car navigation apparatus 920, the in-vehicle network941, and a vehicle-side module 942. The vehicle-side module 942generates vehicle-side data such as a vehicle speed, the number ofengine rotations, or failure information and outputs the generated datato the in-vehicle network 941.

13-3. Third Application Example

FIG. 53 is a block diagram showing an example of a schematicconfiguration of a wireless access point 950 to which a technologyrelated to the present disclosure can be applied. The wireless accesspoint 950 includes a controller 951, a memory 952, an input device 954,a display device 955, a network interface 957, a wireless communicationinterface 963, an antenna switch 964, and an antenna 965.

The controller 951 may be, for example, a CPU or a digital signalprocessor (DSP) and operates various functions (for example, accessrestriction, routing, encryption, firewall, and log management) of theInternet Protocol (IP) layer and higher layers of the wireless accesspoint 950. The memory 952 includes a RAM and a ROM and stores a programto be executed by the controller 951 and various kinds of control data(for example, a terminal list, a routing table, an encryption key,security setting, and log).

The input device 954 includes, for example, buttons or switches andreceives manipulations from a user. The display device 955 includes anLED lamp or the like and displays operation status of the wirelessaccess point 950.

The network interface 957 is a wired communication interface thatconnects the wireless access point 950 to the wired communicationnetwork 958. The network interface 957 may include a plurality ofconnection terminals. The wired communication network 958 may be a LANsuch as Ethernet (registered trademark) or a wide area network (WAN).

The wireless communication interface 963 supports one or more wirelessLAN standards of IEEE 802.11a, 11b, 11g, 11n, 11ac, and 11ad to providea wireless connection to a terminal located nearby as an access point.The wireless communication interface 963 can typically have a basebandprocessor, an RF circuit, a power amplifier, and the like. The wirelesscommunication interface 963 may be a single-chip module on which amemory that stores a communication control program, a processor thatexecutes the program, and a relevant circuit are integrated. The antennaswitch 964 switches a connection destination of the antenna 965 for aplurality of circuits included in the wireless communication interface963. The antenna 965 has a single or a plurality of antenna elements andis used for transmission and reception of wireless signals from thewireless communication interface 963.

In the wireless access point 950 shown in FIG. 53, the control unit 150described with reference to FIG. 5 may be mounted on the wirelesscommunication interface 963. At least some of the functions may bemounted on the controller 951.

The above-described embodiments are examples for embodying the presenttechnology and have correspondence relations with factors in embodimentsand specific inventive factors in the claims. Similarly, specificinventive factors in the claims and factors in embodiments of thepresent technology to which the same names as the specific inventivefactors are given have correspondence relations. However, the presenttechnology is not limited to the embodiments, but may be realized invarious modification forms of the embodiments within the scope withoutdeparting from the gist of the present technology.

The processing orders described in the above-described embodiments maybe ascertained as methods including the series of orders or may beascertained as a program causing a computer to execute the series oforders or a recording medium storing the program. As the recordingmedium, for example, a compact disc (CD), a minidisc (MD), a digitalversatile disc (DVD), a memory card, or a Blu-ray (registered trademark)disc can be used.

The advantageous effects described in the present specification aremerely examples and are not limitative, and other advantageous effectsmay be achieved.

Additionally, the present technology may also be configured as below.

(1)

An information processing device including:

a control unit configured to perform control such that reception of apacket is stopped during the reception according to a first conditionand an operation is performed assuming that a carrier sense is an idlestate for a time from start of the reception of the packet to stop ofthe reception of the packet according to a second condition.

(2)

The information processing device according to (1),

wherein, when the second condition is satisfied after the stop of thereception of the packet, the control unit performs control such that alatency time corresponding to an inter frame space (IFS) does not occur.

(3)

The information processing device according to (1) or (2),

wherein, when the second condition is satisfied after the stop of thereception of the packet, the control unit performs control such that atime length from a transition time of the carrier sense to BUSY at thetime of the reception of the packet to a reception stop time isconverted into a slot time and is subtracted from a backoff counter.

(4)

The information processing device according to (3),

wherein, when a result after the subtraction is a negative value, thecontrol unit treats the result as 0.

(5)

The information processing device according to (3),

wherein, when a result after the subtraction is a negative value, thecontrol unit sets a value obtained by returning the result to a positivevalue corresponding to the negative value so that the value does notexceed the backoff counter before the subtraction.

(6)

The information processing device according to any of (1) to (5),

wherein the first condition includes a condition that a CRC calculationresult obtained when a physical header of the packet during thereception is a target not be identical to CRC information described inthe physical header.

(7)

The information processing device according to (6),

wherein, when information regarding an identifier for identifying anetwork is present in the physical header of the packet, the firstcondition further includes a condition that the information regardingthe identifier be different from a network identifier of a network towhich the information processing device belongs.

(8)

The information processing device according to (6),

wherein the first condition further includes a condition that a preamblecorrelator output level of the packet during the reception in antennainput conversion be less than a threshold derived from informationdescribed in the physical header of the packet.

(9)

The information processing device according to (8),

wherein, when information regarding an identifier for identifying anetwork is present in the physical header of the packet and theinformation regarding the identifier is identical to a networkidentifier of a network to which the information processing devicebelongs, the control unit continues the reception without stopping thereception.

(10)

The information processing device according to (8),

wherein the control unit performs the derivation based on matchingbetween an index described in the physical header of the packet and atable of thresholds shared in advance.

(11)

The information processing device according to (8),

wherein the control unit performs the derivation through conversionbased on a value described in the physical header of the packet andinformation regarding a unit and quantization shared in advance.

(12)

The information processing device according to (1),

wherein the second condition includes the first condition.

(13)

The information processing device according to any of (1) to (10),

wherein the control unit determines necessity and non-necessity of theoperation using a condition that reception power of the packet duringthe reception be less than a pre-decided energy detection threshold, asthe second condition.

(14)

The information processing device according to any of (1) to (10),

wherein the control unit determines necessity and non-necessity of theoperation using a condition that transmission suppression by virtualcarrier sense not be applied at the time of stopping of the reception ofthe packet, as the second condition.

(15)

The information processing device according to any of (1) to (10),

wherein the control unit determines necessity and non-necessity of theoperation using a condition that a CRC calculation result obtained whena physical header of the packet is a target not be identical to CRCinformation described in the physical header and a preamble correlatoroutput level of the packet in antenna input conversion be less than aminimum packet detection threshold among applicable packet detectionthresholds, as the second condition.

(16)

The information processing device according to any of (1) to (15),

wherein, when the second condition is not satisfied after stop of thereception of the packet, the control unit performs control such thattransmission from the information processing device during a continuityperiod of the packet transfer is prohibited.

(17)

The information processing device according to (16),

wherein, when the second condition is not satisfied after the stop ofthe reception of the packet and the transmission from the informationprocessing device during the continuity period of the packet transfer isprohibited, the control unit performs control such that a reply to aframe which is destined for the information processing device andrequests the reply is transmitted when the frame is received.

(18)

An information processing method including:

a first procedure of stopping reception of a packet during the receptionaccording to a first condition; and

a second procedure of performing an operation assuming that a carriersense is an idle state for a time from start of the reception of thepacket to stop of the reception of the packet according to a secondcondition.

(19)

A program causing a computer to execute:

a first procedure of stopping reception of a packet during the receptionaccording to a first condition; and

a second procedure of performing an operation assuming that a carriersense is an idle state for a time from start of the reception of thepacket to stop of the reception of the packet according to a secondcondition.

REFERENCE SIGNS LIST

-   10, 50 communication system-   100 to 104, 200, 201 information processing device-   110 data processing unit-   120 transmission processing unit-   130 modulation and demodulation unit-   140 wireless interface unit-   141 antenna-   150 control unit-   160 memory-   900 smartphone-   901 processor-   902 memory-   903 storage-   904 externally connected interface-   906 camera-   907 sensor-   908 microphone-   909 input device-   910 display device-   911 speaker-   913 wireless communication interface-   914 antenna switch-   915 antenna-   917 bus-   918 battery-   919 auxiliary controller-   920 car navigation apparatus-   921 processor-   922 memory-   924 GPS module-   925 sensor-   926 data interface-   927 content player-   928 storage medium interface-   929 input device-   930 display device-   931 speaker-   933 wireless communication interface-   934 antenna switch-   935 antenna-   938 battery-   941 in-vehicle network-   942 vehicle-side module-   950 wireless access point-   951 controller-   952 memory-   954 input device-   955 display device-   957 network interface-   958 wired communication network-   963 wireless communication interface-   964 antenna switch-   965 antenna

1. An information processing device comprising: a control unitconfigured to perform control such that reception of a packet is stoppedduring the reception according to a first condition and an operation isperformed assuming that a carrier sense is an idle state for a time fromstart of the reception of the packet to stop of the reception of thepacket according to a second condition.
 2. The information processingdevice according to claim 1, wherein, when the second condition issatisfied after the stop of the reception of the packet, the controlunit performs control such that a latency time corresponding to an interframe space (IFS) does not occur.
 3. The information processing deviceaccording to claim 1, wherein, when the second condition is satisfiedafter the stop of the reception of the packet, the control unit performscontrol such that a time length from a transition time of the carriersense to BUSY at the time of the reception of the packet to a receptionstop time is converted into a slot time and is subtracted from a backoffcounter.
 4. The information processing device according to claim 3,wherein, when a result after the subtraction is a negative value, thecontrol unit treats the result as
 0. 5. The information processingdevice according to claim 3, wherein, when a result after thesubtraction is a negative value, the control unit sets a value obtainedby returning the result to a positive value corresponding to thenegative value so that the value does not exceed the backoff counterbefore the subtraction.
 6. The information processing device accordingto claim 1, wherein the first condition includes a condition that a CRCcalculation result obtained when a physical header of the packet duringthe reception is a target not be identical to CRC information describedin the physical header.
 7. The information processing device accordingto claim 6, wherein, when information regarding an identifier foridentifying a network is present in the physical header of the packet,the first condition further includes a condition that the informationregarding the identifier be different from a network identifier of anetwork to which the information processing device belongs.
 8. Theinformation processing device according to claim 6, wherein the firstcondition further includes a condition that a preamble correlator outputlevel of the packet during the reception in antenna input conversion beless than a threshold derived from information described in the physicalheader of the packet.
 9. The information processing device according toclaim 8, wherein, when information regarding an identifier foridentifying a network is present in the physical header of the packetand the information regarding the identifier is identical to a networkidentifier of a network to which the information processing devicebelongs, the control unit continues the reception without stopping thereception.
 10. The information processing device according to claim 8,wherein the control unit performs the derivation based on matchingbetween an index described in the physical header of the packet and atable of thresholds shared in advance.
 11. The information processingdevice according to claim 8, wherein the control unit performs thederivation through conversion based on a value described in the physicalheader of the packet and information regarding a unit and quantizationshared in advance.
 12. The information processing device according toclaim 1, wherein the second condition includes the first condition. 13.The information processing device according to claim 1, wherein thecontrol unit determines necessity and non-necessity of the operationusing a condition that reception power of the packet during thereception be less than a pre-decided energy detection threshold, as thesecond condition.
 14. The information processing device according toclaim 1, wherein the control unit determines necessity and non-necessityof the operation using a condition that transmission suppression byvirtual carrier sense not be applied at the time of stopping of thereception of the packet, as the second condition.
 15. The informationprocessing device according to claim 1, wherein the control unitdetermines necessity and non-necessity of the operation using acondition that a CRC calculation result obtained when a physical headerof the packet is a target not be identical to CRC information describedin the physical header and a preamble correlator output level of thepacket in antenna input conversion be less than a minimum packetdetection threshold among applicable packet detection thresholds, as thesecond condition.
 16. The information processing device according toclaim 1, wherein, when the second condition is not satisfied after stopof the reception of the packet, the control unit performs control suchthat transmission from the information processing device during acontinuity period of the packet transfer is prohibited.
 17. Theinformation processing device according to claim 16, wherein, when thesecond condition is not satisfied after the stop of the reception of thepacket and the transmission from the information processing deviceduring the continuity period of the packet transfer is prohibited, thecontrol unit performs control such that a reply to a frame which isdestined for the information processing device and requests the reply istransmitted when the frame is received.
 18. An information processingmethod comprising: a first procedure of stopping reception of a packetduring the reception according to a first condition; and a secondprocedure of performing an operation assuming that a carrier sense is anidle state for a time from start of the reception of the packet to stopof the reception of the packet according to a second condition.
 19. Aprogram causing a computer to execute: a first procedure of stoppingreception of a packet during the reception according to a firstcondition; and a second procedure of performing an operation assumingthat a carrier sense is an idle state for a time from start of thereception of the packet to stop of the reception of the packet accordingto a second condition.